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201. Titanium hydride (TiH₂) is an example of a:
ⓐ. Saline hydride
ⓑ. Covalent hydride
ⓒ. Metallic hydride
ⓓ. Ionic hydride
Correct Answer: Metallic hydride
Explanation: Titanium hydride (TiH₂) is an example of a metallic hydride, where titanium, a transition metal, forms a solid solution with hydrogen. Metallic hydrides like TiH₂ typically have metallic bonding, where hydrogen atoms occupy interstitial sites within the metal lattice, and these hydrides are good conductors of electricity.
202. Which of the following is a property of metallic hydrides like TiH₂ and PdH₂?
ⓐ. They are highly soluble in water
ⓑ. They conduct electricity in solid form
ⓒ. They are non-reactive with oxygen
ⓓ. They are insoluble in organic solvents
Correct Answer: They conduct electricity in solid form
Explanation: Metallic hydrides, like TiH₂ and PdH₂, are conductors of electricity in solid form due to the metallic bonding in these compounds. The hydrogen atoms occupy interstitial sites in the metal lattice, allowing for the conduction of electrons. This property distinguishes them from ionic hydrides, which do not conduct electricity in the solid state.
203. Palladium hydride (PdH₂) is unique because:
ⓐ. It can absorb large amounts of hydrogen gas
ⓑ. It is a poor conductor of electricity
ⓒ. It forms covalent bonds with hydrogen
ⓓ. It is highly reactive with oxygen
Correct Answer: It can absorb large amounts of hydrogen gas
Explanation: Palladium hydride (PdH₂) is unique because palladium can absorb a large volume of hydrogen gas and form PdH₂, which is a solid solution. Palladium is widely used in hydrogen storage and purification due to this property, where it can reversibly absorb hydrogen without significant volume change, making it useful in various applications, such as hydrogen fuel cells and hydrogen purification systems.
204. Which metal is commonly used in the formation of metallic hydrides for hydrogen storage applications?
ⓐ. Copper
ⓑ. Lead
ⓒ. Zinc
ⓓ. Titanium
Correct Answer: Titanium
Explanation: Titanium is commonly used to form metallic hydrides like TiH₂ for hydrogen storage applications. Titanium hydride has a high hydrogen density and can absorb significant amounts of hydrogen, making it an effective material for hydrogen storage in various applications such as fuel cells and energy systems. Other metals, like palladium (Pd), are also used for similar purposes.
205. Which of the following is true about palladium hydride (PdH₂)?
ⓐ. It is a poor conductor of electricity in solid form
ⓑ. It is formed by the reaction of palladium with oxygen
ⓒ. It can absorb hydrogen and expand in volume
ⓓ. It is a covalent hydride
Correct Answer: It can absorb hydrogen and expand in volume
Explanation: Palladium hydride (PdH₂) has the unique ability to absorb large amounts of hydrogen gas and expand in volume without significant degradation of the structure. This ability makes it highly suitable for hydrogen storage and purification applications. It forms a solid solution of hydrogen in palladium, which is reversible under certain conditions.
206. What is the bonding characteristic of metallic hydrides such as TiH₂ and PdH₂?
ⓐ. Ionic bonding between metal and hydrogen atoms
ⓑ. Metallic bonding with interstitial hydrogen atoms
ⓒ. Covalent bonding between metal and hydrogen atoms
ⓓ. Hydrogen bonding between hydrogen atoms
Correct Answer: Metallic bonding with interstitial hydrogen atoms
Explanation: In metallic hydrides like TiH₂ and PdH₂, the bonding is primarily metallic in nature. The hydrogen atoms occupy interstitial sites within the metal lattice, and the metallic bond allows for the free movement of electrons, giving these hydrides their electrical conductivity. The hydrogen atoms do not form ionic or covalent bonds with the metal but rather interact through the metal’s electron cloud.
207. Which of the following is a characteristic feature of metallic hydrides like PdH₂ and TiH₂?
ⓐ. They are insoluble in water
ⓑ. They are poor conductors of electricity
ⓒ. They are highly soluble in organic solvents
ⓓ. They exhibit high melting points
Correct Answer: They exhibit high melting points
Explanation: Metallic hydrides like PdH₂ and TiH₂ tend to have high melting points due to the strong metallic bonding between the metal and the hydrogen atoms. This bonding contributes to their stability and allows them to withstand high temperatures without decomposing. Additionally, metallic hydrides typically have good electrical conductivity and are stable under standard conditions.
208. Which of the following metals forms a metallic hydride that is used in hydrogen storage?
ⓐ. Silver
ⓑ. Copper
ⓒ. Palladium
ⓓ. Mercury
Correct Answer: Palladium
Explanation: Palladium is a metal that readily forms a metallic hydride (PdH₂), which is widely used in hydrogen storage due to its ability to absorb large amounts of hydrogen gas. This property is particularly useful in hydrogen purification and fuel cell applications. Palladium’s ability to form a solid solution with hydrogen makes it one of the most effective materials for hydrogen storage.
209. Metallic hydrides like TiH₂ and PdH₂ are mainly used in which of the following applications?
ⓐ. As fuels for combustion engines
ⓑ. As catalysts in organic reactions
ⓒ. As materials for hydrogen storage and purification
ⓓ. As water-softening agents
Correct Answer: As materials for hydrogen storage and purification
Explanation: Metallic hydrides like TiH₂ and PdH₂ are primarily used for hydrogen storage and purification. Their ability to absorb large amounts of hydrogen and release it under controlled conditions makes them ideal for use in fuel cells, hydrogen-powered vehicles, and energy systems. These hydrides provide an efficient and compact way to store hydrogen for various applications.
210. In metallic hydrides like PdH₂, hydrogen atoms are:
ⓐ. Bonded covalently to the metal
ⓑ. Occupying interstitial sites in the metal lattice
ⓒ. In the form of hydrogen molecules
ⓓ. Bonded to other hydrogen atoms
Correct Answer: Occupying interstitial sites in the metal lattice
Explanation: In metallic hydrides like PdH₂, hydrogen atoms occupy interstitial sites in the metal lattice. This means that the hydrogen atoms are inserted into the spaces between the metal atoms in the crystal structure. This is characteristic of metallic hydrides, which exhibit metallic bonding, allowing them to conduct electricity and absorb large amounts of hydrogen gas.
211. Interstitial hydrides are formed when:
ⓐ. Hydrogen bonds with a non-metal
ⓑ. Hydrogen atoms form covalent bonds with metals
ⓒ. Hydrogen reacts with non-metals to form ionic compounds
ⓓ. Hydrogen atoms occupy the interstitial spaces in a metal lattice
Correct Answer: Hydrogen atoms occupy the interstitial spaces in a metal lattice
Explanation: Interstitial hydrides are formed when hydrogen atoms occupy the interstitial spaces between metal atoms in a metal lattice. These hydrides typically form when metals with larger atomic radii (transition metals) react with hydrogen. The metal lattice provides enough space for hydrogen atoms to fit without disturbing the overall structure, leading to the formation of solid hydrides.
212. Which of the following is a characteristic property of interstitial hydrides?
ⓐ. They are poor conductors of electricity
ⓑ. They are good conductors of electricity
ⓒ. They are chemically inert
ⓓ. They are highly reactive with oxygen
Correct Answer: They are good conductors of electricity
Explanation: Interstitial hydrides are good conductors of electricity because they retain the metallic bonding between metal atoms in the lattice. This allows for the free movement of electrons, making these hydrides conductors. Unlike ionic hydrides, which do not conduct electricity in solid form, interstitial hydrides exhibit metallic properties, including electrical conductivity.
213. Which of the following metals forms interstitial hydrides?
ⓐ. Sodium
ⓑ. Lithium
ⓒ. Calcium
ⓓ. Titanium
Correct Answer: Titanium
Explanation: Titanium is a transition metal that forms interstitial hydrides. When titanium reacts with hydrogen, the hydrogen atoms occupy the interstitial sites in the titanium lattice, resulting in the formation of titanium hydride (TiH₂). This hydride exhibits metallic properties and is used in hydrogen storage applications. Other transition metals like palladium and zirconium also form interstitial hydrides.
214. The primary use of interstitial hydrides, such as TiH₂, is:
ⓐ. Hydrogen storage
ⓑ. Fuel for combustion engines
ⓒ. Catalyst in organic reactions
ⓓ. As a semiconductor material
Correct Answer: Hydrogen storage
Explanation: Interstitial hydrides such as TiH₂ are primarily used for hydrogen storage. These hydrides can absorb and release hydrogen gas in a controlled manner, making them ideal for use in hydrogen storage systems, fuel cells, and hydrogen-powered vehicles. Their ability to reversibly absorb hydrogen without significant volume change is a key advantage in hydrogen storage applications.
215. Interstitial hydrides are typically formed with which type of metals?
ⓐ. Alkali metals
ⓑ. Noble gases
ⓒ. Transition metals
ⓓ. Lanthanides
Correct Answer: Transition metals
Explanation: Interstitial hydrides are typically formed by transition metals. These metals, such as titanium, palladium, and zirconium, have relatively large atomic radii and can accommodate hydrogen atoms in the interstitial spaces of their metal lattices. This allows the formation of hydrides with metallic properties. Transition metals can absorb significant amounts of hydrogen, which makes them valuable in hydrogen storage and purification applications.
216. What is the structure of interstitial hydrides like TiH₂?
ⓐ. Hydrogen atoms form covalent bonds with metal atoms
ⓑ. Hydrogen atoms occupy voids between metal atoms in the lattice
ⓒ. Hydrogen atoms are bonded directly to other hydrogen atoms
ⓓ. Hydrogen atoms form an ionic bond with metal atoms
Correct Answer: Hydrogen atoms occupy voids between metal atoms in the lattice
Explanation: In interstitial hydrides like TiH₂, hydrogen atoms occupy the interstitial voids between metal atoms in the crystal lattice. This arrangement does not disturb the metallic bonding between metal atoms, allowing the hydride to retain many of the electrical and thermal properties of metals. The hydrogen atoms are not covalently bonded to the metal but are held in place by the metal lattice.
217. The hydrogen atoms in interstitial hydrides are typically in the form of:
ⓐ. Hydride ions (H⁻)
ⓑ. Molecular hydrogen (H₂)
ⓒ. Atomic hydrogen (H)
ⓓ. Protons (H⁺)
Correct Answer: Hydride ions (H⁻)
Explanation: In interstitial hydrides, the hydrogen atoms are typically in the form of hydride ions (H⁻). These hydride ions are produced when hydrogen atoms donate their electrons to the metal, forming an ionic bond with the metal. This gives interstitial hydrides their unique properties, such as the ability to absorb hydrogen and store it in the solid form.
218. Interstitial hydrides such as TiH₂ are most commonly used in:
ⓐ. Hydrogenation reactions
ⓑ. Electrolysis of water
ⓒ. Water purification
ⓓ. Hydrogen storage and release
Correct Answer: Hydrogen storage and release
Explanation: Interstitial hydrides like TiH₂ are widely used in hydrogen storage and release applications. The ability of these hydrides to absorb and desorb hydrogen gas in a controlled manner makes them ideal for storing hydrogen in fuel cells, hydrogen-powered vehicles, and other energy storage systems. Their high hydrogen density and stable structure at room temperature make them a promising material for future energy solutions.
219. Which of the following is true regarding the hydrogen absorption in interstitial hydrides?
ⓐ. Hydrogen is absorbed in the form of molecular hydrogen (H₂)
ⓑ. Hydrogen is absorbed without forming any bond with the metal
ⓒ. Hydrogen forms a solid solution with the metal by occupying interstitial sites
ⓓ. Hydrogen is absorbed only in gas form and cannot form solid solutions
Correct Answer: Hydrogen forms a solid solution with the metal by occupying interstitial sites
Explanation: In interstitial hydrides, hydrogen is absorbed by the metal in the form of hydride ions ($H^-$) and occupies the interstitial sites between metal atoms in the crystal lattice. This process forms a solid solution, where hydrogen is dispersed throughout the metal. This allows for reversible hydrogen absorption and release, making interstitial hydrides ideal for hydrogen storage.
220. What is the primary difference between interstitial hydrides and ionic hydrides?
ⓐ. Interstitial hydrides do not conduct electricity
ⓑ. Ionic hydrides contain hydrogen as $H^-$ ions, while interstitial hydrides contain hydrogen in metal lattices
ⓒ. Ionic hydrides are formed by non-metals, while interstitial hydrides are formed by metals
ⓓ. Interstitial hydrides are unstable at room temperature, unlike ionic hydrides
Correct Answer: Ionic hydrides contain hydrogen as $H^-$ ions, while interstitial hydrides contain hydrogen in metal lattices
Explanation: The primary difference between interstitial hydrides and ionic hydrides is in the structure and bonding. In ionic hydrides, hydrogen exists as $H^-$ ions that are ionically bonded to metal cations (e.g., NaH, CaH₂), while in interstitial hydrides, hydrogen atoms occupy interstitial sites within a metal lattice, forming a solid solution with metallic bonding. This structural difference gives interstitial hydrides their unique properties.
221. Water has a high boiling point compared to other molecules of similar size because:
ⓐ. It has strong covalent bonds
ⓑ. It has low molecular weight
ⓒ. It is a polar molecule
ⓓ. It exhibits hydrogen bonding
Correct Answer: It exhibits hydrogen bonding
Explanation: Water has a high boiling point compared to other molecules of similar size due to the presence of hydrogen bonds between its molecules. These strong intermolecular forces require more energy to break, resulting in a higher boiling point than expected for a molecule of its size. The hydrogen bonds are formed between the hydrogen atom of one molecule and the oxygen atom of another molecule.
222. The density of water is highest at:
ⓐ. 0°C
ⓑ. 4°C
ⓒ. 10°C
ⓓ. 100°C
Correct Answer: 4°C
Explanation: The density of water is highest at 4°C. Below this temperature, water begins to expand as it freezes, which is why ice floats on water. The unusual behavior of water is due to the hydrogen bonds forming a crystalline structure at temperatures below 4°C, making ice less dense than liquid water.
223. Water has a high specific heat capacity, meaning it:
ⓐ. Requires a large amount of heat to raise its temperature
ⓑ. Heats up very quickly
ⓒ. Can easily freeze
ⓓ. Is a poor conductor of heat
Correct Answer: Requires a large amount of heat to raise its temperature
Explanation: Water has a high specific heat capacity, which means it requires a large amount of heat to raise its temperature by 1°C. This property is due to the hydrogen bonds between water molecules, which absorb and store energy. This high specific heat helps regulate temperature in ecosystems and makes water an effective coolant.
224. Water’s high surface tension is mainly due to:
ⓐ. The evaporation of water molecules at the surface
ⓑ. The covalent bonds within water molecules
ⓒ. The ionic interactions between water molecules
ⓓ. The hydrogen bonds between water molecules
Correct Answer: The hydrogen bonds between water molecules
Explanation: Surface tension in water is mainly due to hydrogen bonds between water molecules. The molecules at the surface are attracted to those beneath them, but they do not have other water molecules above them to form bonds. This results in a “tight” surface, allowing water to form droplets and support small objects like insects on the surface.
225. Water is a polar molecule because:
ⓐ. It has a bent structure and an uneven distribution of electrons
ⓑ. It has a tetrahedral structure
ⓒ. It has a straight structure
ⓓ. It has a symmetric electron distribution
Correct Answer: It has a bent structure and an uneven distribution of electrons
Explanation: Water is a polar molecule due to its bent structure and the uneven distribution of electrons. The oxygen atom is more electronegative than hydrogen, pulling the shared electrons towards itself, giving it a partial negative charge and leaving the hydrogens with partial positive charges. This polarity results in water’s ability to dissolve many substances and participate in hydrogen bonding.
226. The heat of vaporization of water is relatively high because:
ⓐ. Water molecules are very small
ⓑ. Water molecules form strong hydrogen bonds
ⓒ. Water is a non-polar molecule
ⓓ. Water does not undergo a phase change easily
Correct Answer: Water molecules form strong hydrogen bonds
Explanation: The high heat of vaporization of water is due to the strong hydrogen bonds between its molecules. To convert water from liquid to gas, these bonds must be broken, which requires a significant amount of heat energy. This property of water plays a key role in regulating temperature in living organisms and climates, as it helps moderate temperature fluctuations.
227. Why does water expand when it freezes?
ⓐ. The hydrogen bonds become stronger
ⓑ. The water molecules move closer together
ⓒ. The hydrogen bonds form an open crystalline structure
ⓓ. The water molecules lose energy
Correct Answer: The hydrogen bonds form an open crystalline structure
Explanation: Water expands when it freezes because the hydrogen bonds form an open crystalline structure. This structure is less dense than the liquid form, which is why ice floats on water. The hydrogen bonds push the molecules farther apart as they arrange themselves into a hexagonal lattice, increasing the volume and lowering the density of solid water (ice).
228. Water is known as the universal solvent because it:
ⓐ. Can dissolve any substance
ⓑ. Can dissolve many ionic and polar substances
ⓒ. Has no charge
ⓓ. Forms strong bonds with non-polar substances
Correct Answer: Can dissolve many ionic and polar substances
Explanation: Water is called the universal solvent because it can dissolve many ionic and polar substances. This is due to its polar nature, where the positive end of water molecules interacts with negative ions, and the negative end interacts with positive ions, allowing water to dissolve salts, sugars, and many other polar compounds.
229. The refractive index of water is approximately:
ⓐ. 1.0
ⓑ. 1.03
ⓒ. 1.11
ⓓ. 1.33
Correct Answer: 1.33
Explanation: The refractive index of water is approximately 1.33, meaning that light travels 1.33 times slower in water than in a vacuum. This property is important in optical applications, including lenses, microscopes, and cameras, as it affects how light is bent when passing through water.
230. Water has the highest dielectric constant among all liquids because:
ⓐ. It is a non-polar molecule
ⓑ. It can dissolve both ionic and non-ionic substances
ⓒ. It can form hydrogen bonds with other molecules
ⓓ. It has a high molecular weight
Correct Answer: It can form hydrogen bonds with other molecules
Explanation: Water has the highest dielectric constant among all liquids because it is a polar molecule capable of forming strong hydrogen bonds. The polarity of water allows it to interact with other charged particles, which helps it to reduce the electrostatic force between ions in solution, making it an excellent solvent for ionic compounds.
231. The structure of a water molecule (H₂O) is best described as:
ⓐ. Linear
ⓑ. Tetrahedral
ⓒ. Bent (V-shaped)
ⓓ. Planar
Correct Answer: Bent (V-shaped)
Explanation: The structure of a water molecule is bent (V-shaped) because of the two lone pairs of electrons on the oxygen atom. The oxygen atom forms covalent bonds with two hydrogen atoms, and the bond angle between the hydrogen atoms is approximately 104.5°. This bent structure is due to electron-electron repulsion from the lone pairs, which forces the hydrogen atoms to be closer together.
232. The bond angle in a water molecule (H₂O) is approximately:
ⓐ. 180°
ⓑ. 109.5°
ⓒ. 101.5°
ⓓ. 104.5°
Correct Answer: 104.5°
Explanation: The bond angle in a water molecule is approximately 104.5°. This angle is slightly less than the ideal 109.5° of a tetrahedral geometry due to the lone pairs of electrons on the oxygen atom, which exert greater repulsion on the bonding pairs of electrons, pushing the hydrogen atoms closer together.
233. Hydrogen bonding in water occurs between:
ⓐ. Two hydrogen atoms
ⓑ. Two oxygen atoms
ⓒ. A hydrogen atom and an oxygen atom in different molecules
ⓓ. Two oxygen atoms in the same molecule
Correct Answer: A hydrogen atom and an oxygen atom in different molecules
Explanation: Hydrogen bonding in water occurs between the hydrogen atom of one water molecule and the oxygen atom of another water molecule. This bond is a weak electrostatic attraction, where the partially positive hydrogen atom is attracted to the partially negative oxygen atom, leading to the unique properties of water, such as its high boiling point and surface tension.
234. The high boiling point of water is mainly due to:
ⓐ. Ionic bonding
ⓑ. Hydrogen bonding
ⓒ. Covalent bonding
ⓓ. Dipole-dipole interactions
Correct Answer: Hydrogen bonding
Explanation: The high boiling point of water is primarily due to the hydrogen bonds between water molecules. These hydrogen bonds are strong enough to require a significant amount of energy to break, which leads to water’s unusually high boiling point compared to other molecules of similar size. Hydrogen bonds also contribute to water’s high specific heat capacity and surface tension.
235. In the structure of water, each oxygen atom forms how many hydrogen bonds?
ⓐ. Two
ⓑ. Three
ⓒ. Four
ⓓ. One
Correct Answer: Two
Explanation: In the structure of water, each oxygen atom can form two hydrogen bonds: one with the hydrogen atom of a neighboring water molecule and another with the oxygen of another molecule. These hydrogen bonds are responsible for water’s unique properties, such as its ability to form ice crystals with a hexagonal structure.
236. Water’s high surface tension is primarily due to:
ⓐ. Ionic bonds between water molecules
ⓑ. Van der Waals forces
ⓒ. Covalent bonds within the water molecule
ⓓ. Hydrogen bonding between water molecules
Correct Answer: Hydrogen bonding between water molecules
Explanation: The high surface tension of water is caused by hydrogen bonding between water molecules. At the surface of the water, molecules are attracted to each other by hydrogen bonds, creating a “tight” surface that resists external force. This is why small insects can walk on water and why water forms droplets instead of spreading out.
237. The ability of water to dissolve many polar and ionic substances is mainly due to:
ⓐ. Its high temperature
ⓑ. Hydrogen bonding
ⓒ. Covalent bonding
ⓓ. Its small molecular size
Correct Answer: Hydrogen bonding
Explanation: Water’s ability to dissolve many polar and ionic substances is mainly due to hydrogen bonding. The polar nature of water molecules allows them to interact with other polar molecules and ions, breaking them apart and dissolving them. This makes water an excellent solvent, often referred to as the “universal solvent.”
238. Which of the following properties of water can be attributed to hydrogen bonding?
ⓐ. High heat capacity
ⓑ. Low freezing point
ⓒ. High vapor pressure
ⓓ. Low boiling point
Correct Answer: High heat capacity
Explanation: Hydrogen bonding is responsible for water’s high heat capacity. Water can absorb a large amount of heat before its temperature rises significantly because the hydrogen bonds between water molecules must first be broken, which requires additional energy. This property helps regulate temperatures in organisms and environments.
239. Water can form hydrogen bonds because it is a polar molecule. This means that:
ⓐ. Water has an even distribution of charge
ⓑ. Water has a positive charge on both hydrogen atoms
ⓒ. Water has a partial positive charge on hydrogen and a partial negative charge on oxygen
ⓓ. Water has no net charge
Correct Answer: Water has a partial positive charge on hydrogen and a partial negative charge on oxygen
Explanation: Water is polar because oxygen is more electronegative than hydrogen, resulting in a partial negative charge on oxygen and a partial positive charge on hydrogen. This separation of charge allows water molecules to interact with each other through hydrogen bonding, where the positive hydrogen atoms are attracted to the negative oxygen atoms of neighboring molecules.
240. Which of the following best describes the interaction responsible for hydrogen bonding in water?
ⓐ. A strong ionic bond between hydrogen and oxygen
ⓑ. A weak electrostatic attraction between hydrogen and oxygen in different molecules
ⓒ. A covalent bond between two hydrogen atoms
ⓓ. A dipole-dipole interaction between hydrogen and hydrogen
Correct Answer: A weak electrostatic attraction between hydrogen and oxygen in different molecules
Explanation: Hydrogen bonding in water is a weak electrostatic attraction between the partially positive hydrogen atom of one water molecule and the partially negative oxygen atom of another water molecule. This is not a full covalent or ionic bond but a weaker, attractive force that plays a major role in water’s unique properties.
241. Water is essential for life on Earth because it:
ⓐ. Regulates atmospheric pressure
ⓑ. Is the primary component of living cells
ⓒ. Is a poor solvent
ⓓ. Is the primary source of energy for plants
Correct Answer: Is the primary component of living cells
Explanation: Water is the primary component of living cells, making up about 70-95% of the cell’s mass. It is involved in numerous biological processes, including nutrient transport, temperature regulation, and biochemical reactions, making it crucial for the survival of all forms of life.
242. Which of the following is a key role of water in photosynthesis?
ⓐ. It acts as a source of carbon
ⓑ. It absorbs light energy for the reaction
ⓒ. It provides electrons for the production of glucose
ⓓ. It prevents the evaporation of oxygen
Correct Answer: It provides electrons for the production of glucose
Explanation: Water plays a critical role in photosynthesis by supplying electrons during the light-dependent reactions. The water molecules are split into oxygen, protons, and electrons, and the electrons are used in the electron transport chain to produce energy for glucose synthesis in plants:
$$2H_2O \rightarrow O_2 + 4H^+ + 4e^-$$
243. Water’s ability to act as a solvent is crucial for:
ⓐ. The movement of ions across cell membranes
ⓑ. The breakdown of lipids in cells
ⓒ. The absorption of sunlight for energy production
ⓓ. The formation of proteins
Correct Answer: The movement of ions across cell membranes
Explanation: Water’s ability to dissolve a wide range of polar and ionic substances makes it essential for the movement of ions across cell membranes. It helps in the transport of nutrients, waste products, and ions within organisms, ensuring cellular functions are maintained.
244. Water plays a vital role in the climate system by:
ⓐ. Absorbing and storing large amounts of heat
ⓑ. Evaporating into the atmosphere and cooling the Earth’s surface
ⓒ. Both A and B
ⓓ. Forming cloud cover that blocks sunlight
Correct Answer: Both A and B
Explanation: Water plays a crucial role in regulating the Earth’s climate. It absorbs and stores large amounts of heat, preventing rapid temperature fluctuations, and it also evaporates from bodies of water into the atmosphere, releasing latent heat and helping to moderate the temperature. Water’s heat capacity and the water cycle are key to stabilizing Earth’s climate.
245. Water is involved in which of the following biological processes?
ⓐ. Photosynthesis
ⓑ. Respiration
ⓒ. Digestion
ⓓ. All of the above
Correct Answer: All of the above
Explanation: Water is involved in many biological processes, including photosynthesis, where it provides electrons for glucose production; respiration, where it participates in metabolic reactions; and digestion, where it helps break down food and transport nutrients. Water is a universal medium in biological systems.
246. Water’s role in maintaining temperature stability in organisms is due to its:
ⓐ. High specific heat capacity
ⓑ. High thermal conductivity
ⓒ. Ability to evaporate easily
ⓓ. Ability to freeze quickly
Correct Answer: High specific heat capacity
Explanation: Water’s high specific heat capacity allows it to absorb and release large amounts of heat without significant changes in temperature. This property helps organisms maintain a stable internal temperature, even in fluctuating external conditions, which is crucial for maintaining metabolic processes.
247. Water is essential in the nitrogen cycle because it:
ⓐ. Breaks down nitrogen into usable forms for plants
ⓑ. Helps fix nitrogen in the soil
ⓒ. Transports nitrogen compounds to plants
ⓓ. Participates in the process of denitrification
Correct Answer: Participates in the process of denitrification
Explanation: Water is involved in the denitrification process, where bacteria in waterlogged soils convert nitrate (NO₃⁻) into nitrogen gas (N₂), which is then released into the atmosphere. This process helps return nitrogen to the atmosphere and completes the nitrogen cycle.
248. Water’s role in the human body includes:
ⓐ. Maintaining blood volume and pressure
ⓑ. Regulating body temperature through sweating
ⓒ. Transporting nutrients and waste products
ⓓ. All of the above
Correct Answer: All of the above
Explanation: Water plays numerous critical roles in the human body. It maintains blood volume and pressure, regulates body temperature through sweating and evaporative cooling, and transports nutrients and waste products within the bloodstream. Water is essential for proper hydration and cellular function.
249. The water cycle is responsible for:
ⓐ. Recycling water between Earth’s surface and atmosphere
ⓑ. Transporting oxygen in the air
ⓒ. Reducing carbon dioxide levels in the atmosphere
ⓓ. Generating energy for ecosystems
Correct Answer: Recycling water between Earth’s surface and atmosphere
Explanation: The water cycle (also known as the hydrological cycle) involves the continuous movement of water between the Earth’s surface and atmosphere. It includes processes such as evaporation, condensation, precipitation, and infiltration, which ensure the constant recycling of water in ecosystems.
250. In aquatic ecosystems, water helps support life by:
ⓐ. Providing a habitat for organisms
ⓑ. Dissolving nutrients for plant and animal uptake
ⓒ. Regulating temperature through heat absorption
ⓓ. All of the above
Correct Answer: All of the above
Explanation: Water plays a critical role in aquatic ecosystems by providing a habitat for organisms, dissolving essential nutrients that plants and animals need, and helping regulate temperature through its high heat capacity. These properties create a stable environment that supports diverse life forms in freshwater and marine ecosystems.
251. Temporary hardness of water is mainly caused by:
ⓐ. Dissolved salts of calcium and magnesium
ⓑ. Dissolved bicarbonates of calcium and magnesium
ⓒ. Presence of chloride salts
ⓓ. Presence of sulfur compounds
Correct Answer: Dissolved bicarbonates of calcium and magnesium
Explanation: Temporary hardness is caused by the presence of dissolved bicarbonates of calcium and magnesium ($Ca(HCO_3)_2$ and $Mg(HCO_3)_2$). When heated, these bicarbonates decompose to form insoluble carbonates, leading to the formation of scale. This type of hardness can be removed by boiling the water.
252. Permanent hardness of water is caused by:
ⓐ. Presence of bicarbonates in water
ⓑ. Presence of suspended solids
ⓒ. Presence of dissolved oxygen
ⓓ. Dissolved chlorides and sulfates of calcium and magnesium
Correct Answer: Dissolved chlorides and sulfates of calcium and magnesium
Explanation: Permanent hardness is caused by the presence of dissolved chlorides and sulfates of calcium and magnesium, such as $CaSO_4$ and $MgCl_2$. Unlike temporary hardness, permanent hardness cannot be removed by boiling. It requires chemical treatments, such as ion exchange or the addition of washing soda.
253. Which of the following is an effective method to remove temporary hardness from water?
ⓐ. Filtration
ⓑ. Boiling
ⓒ. Ion exchange
ⓓ. Distillation
Correct Answer: Boiling
Explanation: Boiling is an effective method to remove temporary hardness. When water containing bicarbonates of calcium and magnesium is heated, the bicarbonates decompose to form insoluble carbonates of calcium and magnesium, which can be removed by filtration. This process reduces the hardness in the water.
254. Which of the following methods is used to remove permanent hardness from water?
ⓐ. Boiling
ⓑ. Filtration
ⓒ. Addition of washing soda
ⓓ. Chlorination
Correct Answer: Addition of washing soda
Explanation: Washing soda (sodium carbonate, $Na_2CO_3$) is commonly used to remove permanent hardness from water. It reacts with the calcium and magnesium salts (chlorides and sulfates) in the water to form insoluble carbonates, which can be easily removed by filtration:
$$Ca^{2+} + Na_2CO_3 \rightarrow CaCO_3 \downarrow$$
This process helps in reducing the hardness of water.
255. Which of the following is a common method used to remove both temporary and permanent hardness from water?
ⓐ. Boiling
ⓑ. Ion exchange
ⓒ. Filtration
ⓓ. Sedimentation
Correct Answer: Ion exchange
Explanation: The ion exchange method is a common method used to remove both temporary and permanent hardness from water. In this process, hardness-causing ions like calcium ($Ca^{2+}$) and magnesium ($Mg^{2+}$) are exchanged with sodium ($Na^+$) or potassium ($K^+$) ions using an ion exchange resin. This method is commonly used in water softeners.
256. The water softening process that uses calcium carbonate (CaCO₃) for hardness removal is called:
ⓐ. Lime-soda process
ⓑ. Ion exchange method
ⓒ. Reverse osmosis
ⓓ. Distillation
Correct Answer: Lime-soda process
Explanation: The lime-soda process is used for water softening and involves the addition of lime ($Ca(OH)_2$) and soda (sodium carbonate, $Na_2CO_3$) to water. Lime reacts with temporary hardness (bicarbonates of calcium and magnesium), while soda reacts with permanent hardness (calcium and magnesium salts like chlorides and sulfates). This process forms insoluble carbonates that can be removed by filtration.
257. In the ion exchange method, which ion typically replaces calcium and magnesium ions in the water?
ⓐ. Sodium (Na⁺)
ⓑ. Chloride (Cl⁻)
ⓒ. Bicarbonate (HCO₃⁻)
ⓓ. Calcium (Ca²⁺)
Correct Answer: Sodium (Na⁺)
Explanation: In the ion exchange method, sodium ions (Na⁺) typically replace the hardness-causing ions like calcium (Ca²⁺) and magnesium (Mg²⁺) in the water. This process involves passing the hard water through a resin that exchanges calcium and magnesium ions with sodium ions, resulting in softened water.
258. Which of the following compounds is used in the removal of both temporary and permanent hardness from water?
ⓐ. Sodium chloride
ⓑ. Calcium sulfate
ⓒ. Sodium bicarbonate
ⓓ. Sodium carbonate
Correct Answer: Sodium carbonate
Explanation: Sodium carbonate (Na₂CO₃), also known as washing soda, is used to remove both temporary and permanent hardness. It reacts with calcium and magnesium salts to form insoluble carbonates, which can then be removed by filtration. This method is effective for both types of hardness and is commonly used in water treatment.
259. Water treated by the ion exchange method is known as:
ⓐ. Hard water
ⓑ. Distilled water
ⓒ. Softened water
ⓓ. Tap water
Correct Answer: Softened water
Explanation: Water treated by the ion exchange method is known as softened water. In this process, calcium and magnesium ions (which cause hardness) are replaced by sodium or potassium ions, making the water soft. Softened water does not form scale and is ideal for household use, especially in washing and laundry applications.
260. Which of the following is an undesirable effect of hard water in domestic use?
ⓐ. Increased soap consumption
ⓑ. Increased oxygen solubility
ⓒ. Lower water temperature
ⓓ. Decreased water viscosity
Correct Answer: Increased soap consumption
Explanation: Hard water contains high levels of calcium and magnesium salts, which react with soap to form insoluble compounds, resulting in increased soap consumption. This leads to more soap being required for cleaning purposes, and it also leaves soap scum on surfaces, making cleaning less effective. Additionally, hard water can cause scale buildup in pipes and appliances.
261. Heavy water (D₂O) differs from regular water (H₂O) in that:
ⓐ. It contains deuterium atoms instead of hydrogen atoms
ⓑ. It has a higher boiling point than regular water
ⓒ. It contains oxygen-18 instead of oxygen-16
ⓓ. It is a more effective solvent than regular water
Correct Answer: It contains deuterium atoms instead of hydrogen atoms
Explanation: Heavy water (D₂O) contains deuterium (D), an isotope of hydrogen, instead of the common hydrogen isotope (H). Deuterium has a neutron in addition to a proton in its nucleus, making D₂O heavier than regular water (H₂O). This results in differences in physical properties, such as a slightly higher boiling point.
262. The primary method for producing heavy water (D₂O) is:
ⓐ. Electrolysis of water
ⓑ. Fractional distillation of water
ⓒ. Liquid-liquid extraction
ⓓ. Electrolysis of hydrogen chloride
Correct Answer: Fractional distillation of water
Explanation: Fractional distillation is the primary method used for producing heavy water. The process relies on the small difference in boiling points between water (H₂O) and heavy water (D₂O). Since D₂O has a slightly higher boiling point, it can be separated from regular water by repeated distillation, allowing for the gradual concentration of D₂O.
263. Which of the following is a property of heavy water (D₂O) compared to regular water (H₂O)?
ⓐ. Higher freezing point
ⓑ. Lower viscosity
ⓒ. Higher density
ⓓ. Higher boiling point
Correct Answer: Higher boiling point
Explanation: Heavy water (D₂O) has a higher boiling point and higher density compared to regular water (H₂O). The increased boiling point is due to the stronger hydrogen bonds in D₂O, which results from the presence of deuterium atoms. The higher density is also a consequence of the heavier deuterium atoms replacing hydrogen.
264. Heavy water is commonly used in:
ⓐ. Agriculture for plant growth
ⓑ. Nuclear reactors as a moderator
ⓒ. Food industry as a preservative
ⓓ. Pharmaceutical industry for drug synthesis
Correct Answer: Nuclear reactors as a moderator
Explanation: Heavy water (D₂O) is used in nuclear reactors as a moderator. In nuclear reactors, heavy water slows down neutrons, which increases the likelihood of a nuclear fission reaction occurring. This property makes D₂O an effective coolant and moderator in reactors that use uranium-235 or deuterium as fuel.
265. The freezing point of heavy water (D₂O) is:
ⓐ. Higher than that of regular water
ⓑ. The same as that of regular water
ⓒ. Lower than that of regular water
ⓓ. Dependent on the concentration of deuterium
Correct Answer: Higher than that of regular water
Explanation: Heavy water (D₂O) has a higher freezing point than regular water. The freezing point of D₂O is around 3.8°C, which is slightly higher than that of H₂O (0°C). This difference is due to the stronger hydrogen bonds formed by deuterium atoms, which require more energy to break.
266. Heavy water (D₂O) is used in biological research because:
ⓐ. It accelerates chemical reactions
ⓑ. It is toxic to most microorganisms
ⓒ. It allows for tracking isotopes in biological systems
ⓓ. It enhances the growth of microorganisms
Correct Answer: It allows for tracking isotopes in biological systems
Explanation: Heavy water (D₂O) is used in biological research to track the movement of isotopes in living organisms. Since deuterium behaves similarly to hydrogen in biological systems, heavy water can be used to trace the incorporation of hydrogen into various biochemical processes, making it a useful tool in studies of metabolism and chemical reactions in cells.
267. The production of heavy water (D₂O) is most commonly carried out using:
ⓐ. The Girdler sulfide process
ⓑ. The Ostwald process
ⓒ. The Haber process
ⓓ. The Solvay process
Correct Answer: The Girdler sulfide process
Explanation: The Girdler sulfide process is the most commonly used method for producing heavy water on an industrial scale. This process involves the exchange of hydrogen and deuterium between hydrogen sulfide and water, with the help of a catalyst, to enrich the concentration of deuterium in the water. It is an efficient method used in large-scale production.
268. Which of the following best describes the effect of heavy water on biological systems?
ⓐ. It enhances metabolic reactions
ⓑ. It has no significant biological effect
ⓒ. It accelerates DNA replication
ⓓ. It is toxic to most living organisms in large amounts
Correct Answer: It is toxic to most living organisms in large amounts
Explanation: Heavy water (D₂O) can be toxic to living organisms in large amounts. While small amounts of D₂O can be tolerated by organisms, it can disrupt biological processes such as cell division and enzyme function because deuterium forms stronger bonds than hydrogen, affecting the normal biochemical reactions in cells.
269. The density of heavy water (D₂O) is approximately:
ⓐ. 1.0 g/cm³
ⓑ. 1.1 g/cm³
ⓒ. 1.2 g/cm³
ⓓ. 1.3 g/cm³
Correct Answer: 1.1 g/cm³
Explanation: The density of heavy water (D₂O) is approximately 1.1 g/cm³, which is higher than that of regular water (H₂O), which has a density of around 1.0 g/cm³. The higher density is due to the presence of the heavier deuterium atoms in place of hydrogen, making D₂O more dense than H₂O.
270. Heavy water (D₂O) is commonly used in which type of nuclear reactor?
ⓐ. Pressurized water reactor
ⓑ. Boiling water reactor
ⓒ. Heavy water reactor
ⓓ. Gas-cooled reactor
Correct Answer: Heavy water reactor
Explanation: Heavy water (D₂O) is used in heavy water reactors (HWR) as a moderator to slow down neutrons during the fission process. These reactors are often used for the generation of nuclear power, especially in countries like Canada, where CANDU reactors use heavy water for moderating and cooling purposes. Heavy water allows for the use of natural uranium as fuel, making it more efficient in certain types of reactors.
271. In a water molecule (H₂O), the hydrogen atoms are:
ⓐ. Covalently bonded to the oxygen atom
ⓑ. Ionic bonds are formed with oxygen
ⓒ. Hydrogen bonds are formed with oxygen
ⓓ. Attached by van der Waals forces
Correct Answer: Covalently bonded to the oxygen atom
Explanation: In a water molecule (H₂O), each hydrogen atom is covalently bonded to the oxygen atom. The oxygen atom shares electrons with the hydrogen atoms, forming two strong covalent bonds. Additionally, these water molecules can form hydrogen bonds with other water molecules, but the O-H bonds within a single molecule are covalent.
272. The hydrogen bonding in water occurs between:
ⓐ. Two hydrogen atoms
ⓑ. Two oxygen atoms
ⓒ. A hydrogen atom and an oxygen atom in different molecules
ⓓ. Two oxygen atoms in the same molecule
Correct Answer: A hydrogen atom and an oxygen atom in different molecules
Explanation: Hydrogen bonding in water occurs between the hydrogen atom of one water molecule and the oxygen atom of a neighboring water molecule. This weak electrostatic attraction plays a key role in water’s high boiling point, surface tension, and its ability to dissolve many substances.
273. The bond angle in a water molecule is approximately:
ⓐ. 120°
ⓑ. 104.5°
ⓒ. 90°
ⓓ. 180°
Correct Answer: 104.5°
Explanation: The bond angle in a water molecule is approximately 104.5°. This angle is slightly smaller than the ideal tetrahedral angle of 109.5° due to the repulsion between the two lone pairs of electrons on the oxygen atom, which forces the hydrogen atoms to be closer together.
274. What makes water a polar molecule?
ⓐ. The oxygen atom is larger than the hydrogen atoms.
ⓑ. The hydrogen atoms share electrons equally with the oxygen atom.
ⓒ. The oxygen atom is more electronegative than the hydrogen atoms, creating a dipole.
ⓓ. The molecule has a linear shape.
Correct Answer: The oxygen atom is more electronegative than the hydrogen atoms, creating a dipole.
Explanation: Water is polar because oxygen is more electronegative than hydrogen, which causes the electrons in the O-H bonds to be drawn closer to the oxygen atom. This creates a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms, resulting in a dipole moment.
275. Hydrogen bonding in water contributes to which of the following properties?
ⓐ. Low boiling point
ⓑ. Decreased viscosity
ⓒ. High solubility for nonpolar substances
ⓓ. High surface tension
Correct Answer: High surface tension
Explanation: Hydrogen bonding in water leads to high surface tension. The attraction between water molecules at the surface creates a “tight” surface that resists external force, allowing small insects to walk on water and forming spherical droplets of water.
276. The oxygen atom in water (H₂O) has a partial negative charge because:
ⓐ. It attracts electrons from hydrogen atoms more strongly due to its higher electronegativity
ⓑ. It shares electrons equally with hydrogen atoms
ⓒ. It repels electrons from hydrogen atoms
ⓓ. It has no charge
Correct Answer: It attracts electrons from hydrogen atoms more strongly due to its higher electronegativity
Explanation: The oxygen atom in water has a partial negative charge because it is more electronegative than hydrogen, meaning it attracts the shared electrons in the O-H bonds more strongly. This causes a concentration of electron density around the oxygen atom, giving it a partial negative charge, while the hydrogen atoms acquire partial positive charges.
277. The phenomenon that causes water to “climb” up a plant stem against gravity is called:
ⓐ. Surface tension
ⓑ. Osmosis
ⓒ. Evaporation
ⓓ. Capillary action
Correct Answer: Capillary action
Explanation: Capillary action occurs when water moves upward through narrow spaces, such as the xylem of plants, due to the adhesive and cohesive forces between water molecules and the walls of the stem. The hydrogen bonding in water contributes to this phenomenon, allowing water to travel against gravity in plants.
278. The reason why water is considered a universal solvent is due to:
ⓐ. Its ability to dissolve all substances
ⓑ. Its non-polar structure
ⓒ. Its polar nature and ability to dissolve many ionic and polar substances
ⓓ. Its low boiling point
Correct Answer: Its polar nature and ability to dissolve many ionic and polar substances
Explanation: Water is called a universal solvent because of its polar nature, which allows it to dissolve many ionic and polar substances. The positive and negative ends of water molecules can surround and separate charged particles, enabling water to dissolve a wide variety of compounds, including salts, sugars, and gases.
279. The high heat of vaporization of water is due to:
ⓐ. The covalent bonds between hydrogen and oxygen
ⓑ. The presence of strong hydrogen bonds between water molecules
ⓒ. The low molecular weight of water
ⓓ. The high specific heat of water
Correct Answer: The presence of strong hydrogen bonds between water molecules
Explanation: The high heat of vaporization of water is due to the hydrogen bonds between water molecules. These bonds must be broken for water to transition from liquid to gas, and this requires a significant amount of energy. This property helps regulate temperature in organisms and ecosystems, as water absorbs and releases heat slowly.
280. In water, each hydrogen bond is approximately:
ⓐ. 1-2 kJ/mol
ⓑ. 50-100 kJ/mol
ⓒ. 20-40 kJ/mol
ⓓ. 5-10 kJ/mol
Correct Answer: 5-10 kJ/mol
Explanation: Each hydrogen bond in water is relatively weak, with a bond energy of approximately 5-10 kJ/mol. While individual hydrogen bonds are weak, the collective network of hydrogen bonds in liquid water gives it its unique properties, such as high boiling point and high surface tension.
281. Heavy water (D₂O) is used as a moderator in nuclear reactors because it:
ⓐ. Reacts with uranium to produce energy
ⓑ. Slows down neutrons without absorbing them
ⓒ. Increases the rate of fission reactions
ⓓ. Cools the reactor core
Correct Answer: Slows down neutrons without absorbing them
Explanation: Heavy water (D₂O) is used as a moderator in nuclear reactors because it slows down neutrons without significantly absorbing them. This allows the neutrons to be more effective in causing fission reactions in uranium-235. The use of heavy water enables reactors to use natural uranium as fuel without needing enrichment.
282. The main advantage of using heavy water (D₂O) as a moderator in nuclear reactors compared to light water (H₂O) is that:
ⓐ. It has a higher neutron absorption cross-section
ⓑ. It can absorb more neutrons and increase fission rates
ⓒ. It is cheaper and easier to produce
ⓓ. It can slow down neutrons effectively without absorbing them
Correct Answer: It can slow down neutrons effectively without absorbing them
Explanation: Heavy water (D₂O) is preferred over light water (H₂O) as a moderator in certain nuclear reactors because it slows down neutrons effectively without absorbing them. This property allows for a more efficient use of fuel, particularly in reactors using natural uranium, as the neutrons remain available for fission reactions.
283. In nuclear reactors, what is the primary role of a moderator like heavy water (D₂O)?
ⓐ. To convert uranium into plutonium
ⓑ. To absorb excess neutrons
ⓒ. To slow down fast neutrons to thermal energies
ⓓ. To cool the reactor core
Correct Answer: To slow down fast neutrons to thermal energies
Explanation: The primary role of a moderator like heavy water (D₂O) is to slow down fast neutrons produced during nuclear fission reactions to thermal (slow) energies. Slow neutrons are more likely to cause further fission reactions in uranium-235, making the reactor more efficient. The moderator does not absorb significant amounts of neutrons, unlike other materials such as boron.
284. One of the uses of heavy water (D₂O) in tracer studies is to:
ⓐ. Track the movement of water in plants
ⓑ. Monitor the concentration of oxygen in the atmosphere
ⓒ. Study chemical reactions in living organisms
ⓓ. Detect the presence of pollutants in the environment
Correct Answer: Track the movement of water in plants
Explanation: In tracer studies, heavy water (D₂O) is used to track the movement of water in biological systems, such as plants. Since deuterium (the isotope of hydrogen in heavy water) behaves similarly to hydrogen but is distinguishable in analysis, it can be used to trace how water moves through plant tissues, into cells, and through various biological processes.
285. In medical tracer studies, heavy water (D₂O) is used to:
ⓐ. Track the distribution of water in the human body
ⓑ. Measure oxygen consumption in cells
ⓒ. Study the reaction rates of enzymes
ⓓ. Detect cancer cells in the bloodstream
Correct Answer: Track the distribution of water in the human body
Explanation: Heavy water (D₂O) is used in medical tracer studies to track the distribution of water in the human body. Since D₂O is easily detectable in body fluids, it allows researchers to monitor how water is distributed and metabolized within the body, providing valuable insights into hydration, cell function, and fluid dynamics.
286. One of the key reasons heavy water (D₂O) is used in nuclear reactors is that it:
ⓐ. Is chemically reactive with uranium
ⓑ. Reacts with neutrons to generate energy
ⓒ. Has a lower neutron absorption rate compared to light water
ⓓ. Is cheaper to manufacture than light water
Correct Answer: Has a lower neutron absorption rate compared to light water
Explanation: Heavy water (D₂O) has a lower neutron absorption rate than light water (H₂O), making it more effective as a moderator in nuclear reactors. This allows more neutrons to be available for fission reactions, which increases the reactor’s efficiency and enables the use of natural uranium without requiring enrichment.
287. In tracer studies, why is heavy water (D₂O) preferred over regular water (H₂O)?
ⓐ. It has a longer half-life
ⓑ. It is non-toxic
ⓒ. It has a higher solubility
ⓓ. It can be easily detected due to its distinct isotope
Correct Answer: It can be easily detected due to its distinct isotope
Explanation: Heavy water (D₂O) is preferred in tracer studies because it contains deuterium (D), an isotope of hydrogen, which can be easily detected using specialized instruments. This allows researchers to track the movement of water in various biological and environmental systems with high precision.
288. Heavy water (D₂O) is used in nuclear reactors because it allows for the use of:
ⓐ. Low enriched uranium
ⓑ. High enriched uranium
ⓒ. Natural uranium
ⓓ. Plutonium
Correct Answer: Natural uranium
Explanation: Heavy water (D₂O) is used in nuclear reactors because it allows for the use of natural uranium as fuel. In reactors that use light water as a moderator, uranium must be enriched to increase the proportion of uranium-235. However, heavy water reactors can effectively use natural uranium without the need for enrichment, making them more efficient and cost-effective in certain applications.
289. Which of the following is a benefit of using heavy water (D₂O) in tracer studies?
ⓐ. It can easily bond with other atoms to form compounds
ⓑ. It behaves identically to regular water in all biological systems
ⓒ. It accelerates metabolic reactions in cells
ⓓ. It can be traced and distinguished from regular water due to the isotope deuterium
Correct Answer: It can be traced and distinguished from regular water due to the isotope deuterium
Explanation: The key benefit of using heavy water (D₂O) in tracer studies is that deuterium, the isotope of hydrogen in D₂O, can be easily traced and distinguished from regular hydrogen due to its unique mass and properties. This allows researchers to monitor water movement and trace metabolic processes with high accuracy in living systems.
290. In addition to nuclear reactors, heavy water (D₂O) is also used in:
ⓐ. Studies of plant water transport
ⓑ. Particle accelerators
ⓒ. Thermonuclear reactors
ⓓ. Solar energy production
Correct Answer: Studies of plant water transport
Explanation: Heavy water (D₂O) is used in studies of plant water transport. By replacing regular water with D₂O in plants, researchers can trace how water moves through the plant system. This helps to understand plant hydration, water uptake, and distribution within tissues, contributing to agricultural and ecological research.
291. One of the primary advantages of hydrogen fuel over traditional fossil fuels is that it:
ⓐ. Releases carbon dioxide when burned
ⓑ. Has a higher energy density than gasoline
ⓒ. Produces only water as a byproduct when combusted
ⓓ. Is cheaper to produce than natural gas
Correct Answer: Produces only water as a byproduct when combusted
Explanation: Hydrogen fuel is considered environmentally friendly because when it is used in fuel cells or combusted, it produces only water vapor (H₂O) as a byproduct. This makes it a clean energy source, unlike fossil fuels, which release carbon dioxide (CO₂) and other pollutants when burned.
292. Hydrogen fuel is considered a clean energy source because it:
ⓐ. Emits no greenhouse gases during combustion
ⓑ. Requires no energy for production
ⓒ. Is more expensive than other fuels
ⓓ. Requires fossil fuels for its production
Correct Answer: Emits no greenhouse gases during combustion
Explanation: Hydrogen fuel is considered clean because when it is combusted or used in fuel cells, it produces only water as a byproduct. Unlike fossil fuels, hydrogen combustion does not release greenhouse gases like carbon dioxide (CO₂), making it a key potential solution for reducing global warming and air pollution.
293. One of the key advantages of using hydrogen as a fuel is that it:
ⓐ. Can be stored easily in liquid form
ⓑ. Has a high energy content per unit mass
ⓒ. Is widely available as a natural resource
ⓓ. Does not require specialized infrastructure for transport
Correct Answer: Has a high energy content per unit mass
Explanation: Hydrogen has a high energy content per unit mass, making it an efficient energy carrier. It contains more energy per kilogram than other fuels, such as gasoline or natural gas, which makes it an attractive option for use in applications like fuel cells and electric vehicles, where lightweight fuel storage is crucial.
294. Hydrogen fuel can be used to power vehicles because it:
ⓐ. Is cheaper than electricity
ⓑ. Has a high energy density, allowing for long travel distances
ⓒ. Is widely available in nature
ⓓ. Requires no fuel infrastructure
Correct Answer: Has a high energy density, allowing for long travel distances
Explanation: Hydrogen fuel has a high energy density, meaning that it provides a large amount of energy per unit of weight, which is important for powering vehicles. This high energy density allows hydrogen-powered vehicles to travel longer distances compared to electric vehicles that rely on batteries with lower energy densities.
295. A major environmental advantage of using hydrogen as fuel is that it:
ⓐ. Releases carbon dioxide when used
ⓑ. Is derived from fossil fuels
ⓒ. Requires the destruction of natural habitats for extraction
ⓓ. Produces no harmful emissions during use
Correct Answer: Produces no harmful emissions during use
Explanation: The major environmental advantage of using hydrogen as a fuel is that it produces no harmful emissions when used in fuel cells or combustion. The only byproduct of hydrogen fuel use is water vapor, which makes it a zero-emission energy source, contributing to cleaner air and a reduction in greenhouse gases.
296. Hydrogen fuel cells are advantageous because they:
ⓐ. Produce electricity with only water and heat as byproducts
ⓑ. Have very low efficiency compared to traditional engines
ⓒ. Require fossil fuels to operate
ⓓ. Are not scalable for large-scale applications
Correct Answer: Produce electricity with only water and heat as byproducts
Explanation: Hydrogen fuel cells generate electricity through an electrochemical process that combines hydrogen and oxygen. The only byproducts of this process are water and heat, making fuel cells a clean and efficient method of generating electricity without harmful emissions. This is one of the main advantages of hydrogen fuel cells compared to conventional combustion engines.
297. Which of the following is an advantage of using hydrogen as a fuel for transportation?
ⓐ. Hydrogen is a fossil fuel
ⓑ. Hydrogen fuel infrastructure is already widespread
ⓒ. Hydrogen fuel cells are more energy-efficient than internal combustion engines
ⓓ. Hydrogen is more expensive than gasoline
Correct Answer: Hydrogen fuel cells are more energy-efficient than internal combustion engines
Explanation: Hydrogen fuel cells are more energy-efficient than traditional internal combustion engines because they convert chemical energy directly into electrical energy, avoiding the energy losses associated with mechanical processes like combustion and friction. This leads to higher overall efficiency, especially in hydrogen-powered electric vehicles.
298. One of the challenges of using hydrogen as a fuel is that it:
ⓐ. Cannot be produced from renewable sources
ⓑ. Has no applications outside of transportation
ⓒ. Is a liquid at room temperature
ⓓ. Requires complex and expensive storage and transportation infrastructure
Correct Answer: Requires complex and expensive storage and transportation infrastructure
Explanation: One of the challenges of using hydrogen as a fuel is that it requires specialized storage and transportation infrastructure. Hydrogen is difficult to store because it is the smallest and lightest molecule, which requires high-pressure tanks or cryogenic systems for efficient storage. This makes it more expensive to transport and store compared to conventional fuels like gasoline.
299. Hydrogen fuel is considered a renewable energy source when it is produced by:
ⓐ. Electrolysis of water using electricity from renewable sources
ⓑ. Reacting hydrogen with natural gas
ⓒ. Using coal as a feedstock
ⓓ. Combustion of fossil fuels
Correct Answer: Electrolysis of water using electricity from renewable sources
Explanation: Hydrogen is considered renewable when produced by electrolysis of water using electricity from renewable sources, such as wind or solar power. This method of hydrogen production does not rely on fossil fuels and produces green hydrogen, which is a sustainable and clean energy source for the future.
300. Hydrogen fuel has the potential to reduce greenhouse gas emissions primarily because it:
ⓐ. Emits carbon dioxide when burned
ⓑ. Releases water vapor instead of pollutants when used
ⓒ. Requires large amounts of energy to produce
ⓓ. Is derived from fossil fuels
Correct Answer: Releases water vapor instead of pollutants when used
Explanation: Hydrogen fuel has the potential to reduce greenhouse gas emissions because, when used in fuel cells or combusted, it produces only water vapor as a byproduct. This makes hydrogen a zero-emission energy source, unlike fossil fuels, which release carbon dioxide (CO₂) and other pollutants into the atmosphere.
Welcome to Class 11 Chemistry MCQs – Chapter 9: Hydrogen (Part 3). This part delves into 100 more MCQs on the properties and reactions of hydrogen in various forms, including its role in acid-base reactions, hydrogen bonding, and industrial processes.
- 👉 Total in chapter: 343 MCQs
- 👉 This page contains: 100 solved MCQs
- 👉 Best for: Board exams, JEE, NEET
- 👉 Continue to Part 4 for the final set