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301. The most common method for storing hydrogen is:
ⓐ. Cryogenic storage as a liquid
ⓑ. Absorption in metal hydrides
ⓒ. Compression in high-pressure tanks
ⓓ. Dissolution in organic solvents
Correct Answer: Compression in high-pressure tanks
Explanation: The most common method for storing hydrogen is by compressing it in high-pressure tanks. This allows hydrogen to be stored at a higher density, making it more practical for transportation and use in fuel cells. Compression is a well-established and efficient method for hydrogen storage, although it requires specialized tanks to handle the high pressure.
302. In cryogenic hydrogen storage, hydrogen is stored as a:
ⓐ. Gas at room temperature
ⓑ. Solid at very low temperatures
ⓒ. Mixture with other gases
ⓓ. Liquid at extremely low temperatures
Correct Answer: Liquid at extremely low temperatures
Explanation: Cryogenic hydrogen storage involves cooling hydrogen to extremely low temperatures (below its boiling point of -252.87°C) to convert it into a liquid. This allows hydrogen to be stored at a higher density than in its gaseous form, making it more efficient for transport and use in various applications.
303. Which of the following is a disadvantage of storing hydrogen as a liquid?
ⓐ. It requires cryogenic temperatures and specialized infrastructure
ⓑ. Hydrogen can be stored indefinitely as a liquid
ⓒ. It requires minimal energy to maintain the liquid state
ⓓ. It is cheaper than compressing hydrogen gas
Correct Answer: It requires cryogenic temperatures and specialized infrastructure
Explanation: Storing hydrogen as a liquid requires cryogenic temperatures, which means that the hydrogen must be kept at extremely low temperatures (-252.87°C). This requires significant energy for refrigeration and specialized infrastructure, making it a more expensive and energy-intensive storage method compared to compressed gas storage.
304. Which of the following methods is used to transport hydrogen over long distances?
ⓐ. By truck in compressed gas form
ⓑ. By pipeline as a compressed gas or liquid
ⓒ. By rail in metal hydrides
ⓓ. By sea in dissolved form
Correct Answer: By pipeline as a compressed gas or liquid
Explanation: Hydrogen is commonly transported over long distances through pipelines, either as a compressed gas or liquid. Pipelines allow for continuous, large-scale transportation of hydrogen, making it an effective method for delivering hydrogen to refueling stations, industries, and other applications. Special pipelines are designed to handle hydrogen’s low density and its tendency to leak.
305. What is the primary challenge associated with the transportation of hydrogen gas?
ⓐ. Hydrogen has a high density and is easy to transport
ⓑ. Hydrogen is reactive and causes pipelines to corrode
ⓒ. Hydrogen is highly flammable and requires special safety measures
ⓓ. Hydrogen has a high boiling point and is difficult to liquefy
Correct Answer: Hydrogen is highly flammable and requires special safety measures
Explanation: The primary challenge with transporting hydrogen gas is that it is highly flammable and requires special safety measures during storage and transportation. Hydrogen must be handled carefully to prevent leaks and explosions, as it is highly flammable in certain concentrations and reacts explosively with oxygen.
306. Which of the following materials is commonly used for the construction of high-pressure hydrogen storage tanks?
ⓐ. Aluminum
ⓑ. Steel
ⓒ. Copper
ⓓ. Carbon fiber composites
Correct Answer: Carbon fiber composites
Explanation: Carbon fiber composites are commonly used for the construction of high-pressure hydrogen storage tanks because they are lightweight, strong, and capable of withstanding the high pressures required for storing hydrogen gas. These materials offer a good balance of strength and weight, making them ideal for use in vehicles, storage, and transportation systems.
307. A key advantage of using metal hydrides for hydrogen storage is:
ⓐ. High storage capacity at room temperature
ⓑ. No need for cryogenic temperatures
ⓒ. Simplicity of the storage system
ⓓ. Low cost of the materials
Correct Answer: No need for cryogenic temperatures
Explanation: One key advantage of using metal hydrides for hydrogen storage is that they do not require cryogenic temperatures. Metal hydrides absorb hydrogen gas into their solid structure and release it when heated. This method allows hydrogen to be stored at ambient temperatures and relatively low pressures, making it safer and less energy-intensive than cryogenic storage.
308. Which of the following gases is often mixed with hydrogen during transportation to improve its handling and storage?
ⓐ. Nitrogen
ⓑ. Oxygen
ⓒ. Carbon dioxide
ⓓ. Helium
Correct Answer: Nitrogen
Explanation: Nitrogen is often mixed with hydrogen during transportation to improve safety and reduce the risk of explosion. Nitrogen is inert and does not react with hydrogen, making it a safe diluent in hydrogen pipelines or during compression, reducing the flammability of the hydrogen and preventing uncontrolled reactions.
309. One of the key concerns with the long-term storage of hydrogen is:
ⓐ. Its inability to liquefy
ⓑ. Its tendency to diffuse through materials and escape
ⓒ. Its corrosive nature
ⓓ. Its excessive heat generation
Correct Answer: Its tendency to diffuse through materials and escape
Explanation: One of the key concerns with the long-term storage of hydrogen is its tendency to diffuse through materials and escape. This is particularly problematic in pipelines and storage tanks, where hydrogen’s small size allows it to slowly leak through materials, especially metals. This phenomenon, known as hydrogen embrittlement, can also weaken metal storage tanks and infrastructure over time.
310. Which of the following is a potential future method for hydrogen transport and storage?
ⓐ. Transporting hydrogen as a solid at room temperature
ⓑ. Storing hydrogen in liquid form in large underground reservoirs
ⓒ. Using ammonia (NH₃) as a hydrogen carrier
ⓓ. Using hydrogen peroxide as a carrier
Correct Answer: Using ammonia (NH₃) as a hydrogen carrier
Explanation: One potential future method for hydrogen transport is to use ammonia (NH₃) as a hydrogen carrier. Ammonia can be easily liquefied and transported at relatively low pressures. It contains a high hydrogen content and can be converted back into hydrogen at the destination, providing a viable and efficient way to store and transport hydrogen over long distances, especially in regions lacking direct access to hydrogen infrastructure.
311. The main function of a hydrogen fuel cell is to:
ⓐ. Store hydrogen for later use
ⓑ. Convert hydrogen and oxygen into electricity
ⓒ. Split water molecules into hydrogen and oxygen
ⓓ. Produce hydrogen gas from natural gas
Correct Answer: Convert hydrogen and oxygen into electricity
Explanation: The main function of a hydrogen fuel cell is to convert hydrogen and oxygen into electricity through an electrochemical process. In this process, hydrogen gas reacts with oxygen from the air, producing electricity, water, and heat as byproducts. This clean energy technology is used in a variety of applications, including vehicles and stationary power generation.
312. The byproducts of a hydrogen fuel cell are:
ⓐ. Carbon dioxide and water
ⓑ. Carbon monoxide and heat
ⓒ. Oxygen and heat
ⓓ. Water and heat
Correct Answer: Water and heat
Explanation: The byproducts of a hydrogen fuel cell are water (H₂O) and heat. When hydrogen gas (H₂) reacts with oxygen (O₂) in the fuel cell, the reaction produces electricity, with water vapor and heat being released. This makes hydrogen fuel cells a clean energy source, as they do not emit pollutants like carbon dioxide (CO₂).
313. Hydrogen fuel cells are considered an important technology for clean energy because they:
ⓐ. Emit only oxygen as a byproduct
ⓑ. Have a high energy efficiency and produce no harmful emissions
ⓒ. Require fossil fuels for operation
ⓓ. Consume large amounts of energy during operation
Correct Answer: Have a high energy efficiency and produce no harmful emissions
Explanation: Hydrogen fuel cells are considered a key technology for clean energy because they have high energy efficiency and produce no harmful emissions. The only byproducts are water and heat, making them an ideal solution for reducing air pollution and greenhouse gas emissions, especially in transportation and power generation.
314. Which of the following is an advantage of using hydrogen fuel cells over traditional internal combustion engines?
ⓐ. Higher efficiency and fewer emissions
ⓑ. They run on fossil fuels
ⓒ. They produce significant amounts of carbon dioxide
ⓓ. They are more costly to operate
Correct Answer: Higher efficiency and fewer emissions
Explanation: Hydrogen fuel cells offer the advantage of higher efficiency compared to internal combustion engines and produce fewer emissions. While internal combustion engines burn fuel and emit pollutants like carbon dioxide (CO₂), hydrogen fuel cells only produce water vapor and heat as byproducts, making them much cleaner and more efficient.
315. In a hydrogen fuel cell, the anode is responsible for:
ⓐ. Taking in oxygen
ⓑ. Producing hydrogen gas
ⓒ. Splitting hydrogen molecules into protons and electrons
ⓓ. Generating electricity
Correct Answer: Splitting hydrogen molecules into protons and electrons
Explanation: In a hydrogen fuel cell, the anode is responsible for splitting hydrogen molecules (H₂) into protons (H⁺) and electrons (e⁻). The electrons travel through an external circuit to generate electricity, while the protons move through the electrolyte to the cathode, where they combine with oxygen to form water.
316. What is the role of the electrolyte in a hydrogen fuel cell?
ⓐ. To facilitate the flow of protons from the anode to the cathode
ⓑ. To separate hydrogen and oxygen in the reaction
ⓒ. To conduct electricity between the anode and cathode
ⓓ. To generate hydrogen gas from water
Correct Answer: To facilitate the flow of protons from the anode to the cathode
Explanation: The electrolyte in a hydrogen fuel cell facilitates the flow of protons (H⁺) from the anode to the cathode. The electrolyte is typically a proton-conducting material, such as phosphoric acid or a solid polymer membrane, which allows protons to pass through while blocking electrons. This separation of charge helps create an electric current that powers the fuel cell.
317. One of the main challenges of hydrogen fuel cell technology is:
ⓐ. Lack of hydrogen fuel availability
ⓑ. High operating temperature
ⓒ. The high cost of producing hydrogen
ⓓ. The production of harmful emissions
Correct Answer: The high cost of producing hydrogen
Explanation: One of the main challenges of hydrogen fuel cell technology is the high cost of producing hydrogen. While hydrogen can be produced through various methods, such as electrolysis or steam methane reforming, the production costs, particularly for green hydrogen (produced using renewable energy), are currently high compared to conventional fuels. Reducing these costs is a major focus for improving the viability of hydrogen fuel cells as a widespread clean energy solution.
318. Hydrogen fuel cells can be used in which of the following applications?
ⓐ. Powering vehicles such as cars and buses
ⓑ. Providing backup power for homes and businesses
ⓒ. Generating electricity for large-scale industrial applications
ⓓ. All of the above
Correct Answer: All of the above
Explanation: Hydrogen fuel cells can be used in a wide range of applications, including powering vehicles such as cars and buses, providing backup power for homes and businesses, and generating electricity for large-scale industrial applications. The versatility of hydrogen fuel cells makes them an attractive option for clean energy solutions across various sectors.
319. The efficiency of a hydrogen fuel cell is primarily determined by:
ⓐ. The type of hydrogen used
ⓑ. The size of the fuel cell
ⓒ. The temperature at which it operates
ⓓ. The ability to convert chemical energy into electricity
Correct Answer: The ability to convert chemical energy into electricity
Explanation: The efficiency of a hydrogen fuel cell is primarily determined by its ability to convert chemical energy (from hydrogen) directly into electricity through an electrochemical reaction. Fuel cells are highly efficient because they bypass the mechanical steps involved in combustion, converting energy more directly and with less loss compared to internal combustion engines.
320. Hydrogen fuel cells are considered a promising solution for reducing carbon emissions in the transportation sector because:
ⓐ. They use electricity generated from fossil fuels
ⓑ. They emit only water vapor as a byproduct
ⓒ. They operate at very high temperatures
ⓓ. They produce significant amounts of carbon dioxide
Correct Answer: They emit only water vapor as a byproduct
Explanation: Hydrogen fuel cells are considered a promising solution for reducing carbon emissions in the transportation sector because they produce only water vapor as a byproduct when hydrogen reacts with oxygen to generate electricity. Unlike traditional internal combustion engines, which release harmful pollutants such as carbon dioxide, hydrogen fuel cells offer a clean alternative for powering vehicles.
321. Which of the following chemical equations represents a combination reaction?
ⓐ. $2NaCl + F_2 \rightarrow 2NaF + Cl_2$
ⓑ. $C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$
ⓒ. $2KClO_3 \xrightarrow{heat} 2KCl + 3O_2$
ⓓ. $CaO + H_2O \rightarrow Ca(OH)_2$
Correct Answer: $CaO + H_2O \rightarrow Ca(OH)_2$
Explanation: A combination reaction involves the combination of two or more reactants to form a single product. In this case, calcium oxide (CaO) combines with water (H₂O) to form calcium hydroxide (Ca(OH)₂). The other reactions are examples of decomposition, combustion, and displacement reactions, respectively.
322. The equation $2Na + Cl_2 \rightarrow 2NaCl$ is an example of which type of reaction?
ⓐ. Synthesis reaction
ⓑ. Decomposition reaction
ⓒ. Single displacement reaction
ⓓ. Double displacement reaction
Correct Answer: Synthesis reaction
Explanation: The given equation is a synthesis reaction (also known as a combination reaction) because two reactants, sodium (Na) and chlorine (Cl₂), combine to form a single product, sodium chloride (NaCl). This type of reaction involves the combination of two simpler substances to form a more complex product.
323. Which of the following reactions is an example of a redox reaction?
ⓐ. $H_2 + Cl_2 \rightarrow 2HCl$
ⓑ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓒ. $FeSO_4 \rightarrow Fe_2O_3 + SO_2$
ⓓ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Correct Answer: $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Explanation: A redox reaction involves the transfer of electrons between reactants. In this case, zinc (Zn) displaces copper (Cu) from copper sulfate ($CuSO_4$), with zinc being oxidized (losing electrons) and copper being reduced (gaining electrons). The other reactions are not redox reactions because they either do not involve electron transfer or are acid-base reactions.
324. Which of the following equations is an example of a double displacement reaction?
ⓐ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓑ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓒ. $2H_2 + O_2 \rightarrow 2H_2O$
ⓓ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Correct Answer: $NaOH + HCl \rightarrow NaCl + H_2O$
Explanation: A double displacement reaction (also known as a precipitation reaction) involves the exchange of ions between two compounds to form two new products. In this case, sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl) to form sodium chloride (NaCl) and water (H₂O). The other reactions are synthesis, decomposition, and redox reactions.
325. Which of the following is an example of a displacement reaction?
ⓐ. $2NaCl + F_2 \rightarrow 2NaF + Cl_2$
ⓑ. $C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$
ⓒ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓓ. $NaOH + HCl \rightarrow NaCl + H_2O$
Correct Answer: $2NaCl + F_2 \rightarrow 2NaF + Cl_2$
Explanation: A displacement reaction (also known as a replacement reaction) involves one element displacing another from a compound. In this case, fluorine (F₂) displaces chlorine (Cl) from sodium chloride (NaCl) to form sodium fluoride (NaF) and chlorine gas (Cl₂). The other reactions are combustion, decomposition, and acid-base neutralization reactions.
326. The reaction $2HgO \rightarrow 2Hg + O_2$ is an example of a:
ⓐ. Synthesis reaction
ⓑ. Decomposition reaction
ⓒ. Single displacement reaction
ⓓ. Double displacement reaction
Correct Answer: Decomposition reaction
Explanation: This is an example of a decomposition reaction, where a single reactant, mercury(II) oxide (HgO), breaks down into two simpler products, mercury (Hg) and oxygen gas (O₂). Decomposition reactions involve the breakdown of a compound into simpler substances, typically by heating or other forms of energy.
327. Which of the following reactions is an example of a combustion reaction?
ⓐ. $2H_2 + O_2 \rightarrow 2H_2O$
ⓑ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓒ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Correct Answer: $2H_2 + O_2 \rightarrow 2H_2O$
Explanation: A combustion reaction occurs when a substance reacts with oxygen to produce energy, typically in the form of heat and light. In this case, hydrogen gas (H₂) reacts with oxygen (O₂) to form water (H₂O), releasing energy. Combustion reactions generally involve the burning of fuels.
328. Which of the following is a characteristic feature of a redox reaction?
ⓐ. The reaction forms precipitates
ⓑ. The products are always ionic compounds
ⓒ. The reaction requires an acid or base catalyst
ⓓ. The reaction involves the exchange of electrons between reactants
Correct Answer: The reaction involves the exchange of electrons between reactants
Explanation: Redox reactions (reduction-oxidation reactions) involve the transfer of electrons between reactants. One reactant is oxidized (loses electrons), and the other is reduced (gains electrons). This electron transfer is the defining feature of redox reactions, which occur in processes like combustion, respiration, and corrosion.
329. Which of the following reactions is an example of a disproportionation reaction?
ⓐ. $2Cl^- + H_2O \rightarrow Cl_2 + 2OH^-$
ⓑ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
ⓒ. $2KClO_3 \xrightarrow{heat} 2KCl + 3O_2$
ⓓ. $H_2 + Cl_2 \rightarrow 2HCl$
Correct Answer: $2Cl^- + H_2O \rightarrow Cl_2 + 2OH^-$
Explanation: A disproportionation reaction is a type of redox reaction in which a single substance is both oxidized and reduced. In the reaction $2Cl^- + H_2O \rightarrow Cl_2 + 2OH^-$, chloride ions ($Cl^-$) undergo both oxidation (to form chlorine gas, $Cl_2$) and reduction (to form hydroxide ions, $OH^-$).
330. In the reaction $N_2 + 3H_2 \rightarrow 2NH_3$, the type of reaction is:
ⓐ. Displacement reaction
ⓑ. Decomposition reaction
ⓒ. Redox reaction
ⓓ. Synthesis reaction
Correct Answer: Synthesis reaction
Explanation: The reaction $N_2 + 3H_2 \rightarrow 2NH_3$ is an example of a synthesis reaction (also known as a combination reaction). In this type of reaction, two or more reactants combine to form a single product. In this case, nitrogen gas (N₂) and hydrogen gas (H₂) combine to form ammonia (NH₃).
331. Which of the following is an example of a redox reaction?
ⓐ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓑ. $H_2 + O_2 \rightarrow H_2O$
ⓒ. $AgNO_3 + NaCl \rightarrow AgCl + NaNO_3$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Correct Answer: $H_2 + O_2 \rightarrow H_2O$
Explanation: This is a redox reaction because it involves the transfer of electrons. In the reaction, hydrogen (H₂) is oxidized to form H⁺ ions, and oxygen (O₂) is reduced to form water (H₂O). The oxidation state of hydrogen changes from 0 to +1, and oxygen changes from 0 to -2.
332. Which of the following chemical reactions is an example of a decomposition reaction?
ⓐ. $2Na + Cl_2 \rightarrow 2NaCl$
ⓑ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓒ. $H_2 + Cl_2 \rightarrow 2HCl$
ⓓ. $NaOH + HCl \rightarrow NaCl + H_2O$
Correct Answer: $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Explanation: A decomposition reaction involves the breakdown of a single compound into two or more simpler substances. In this case, calcium carbonate (CaCO₃) decomposes into calcium oxide (CaO) and carbon dioxide (CO₂) when heated.
333. Which of the following reactions represents a displacement reaction?
ⓐ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
ⓑ. $2H_2 + O_2 \rightarrow 2H_2O$
ⓒ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓓ. $NaOH + HCl \rightarrow NaCl + H_2O$
Correct Answer: $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Explanation: In a displacement reaction, one element displaces another from a compound. In this case, zinc (Zn) displaces copper (Cu) from copper sulfate (CuSO₄), forming zinc sulfate (ZnSO₄) and copper metal (Cu).
334. The reaction $N_2 + 3H_2 \rightarrow 2NH_3$ is an example of a:
ⓐ. Decomposition reaction
ⓑ. Redox reaction
ⓒ. Synthesis reaction
ⓓ. Double displacement reaction
Correct Answer: Synthesis reaction
Explanation: This is a synthesis reaction where two or more reactants (nitrogen and hydrogen) combine to form a more complex product (ammonia, NH₃). Synthesis reactions involve the combination of simple substances to form more complex molecules.
335. Which of the following reactions is an example of a combustion reaction?
ⓐ. $2H_2 + O_2 \rightarrow 2H_2O$
ⓑ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓒ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Correct Answer: $2H_2 + O_2 \rightarrow 2H_2O$
Explanation: A combustion reaction occurs when a substance reacts with oxygen to produce energy, typically in the form of heat and light. In this case, hydrogen reacts with oxygen to form water (H₂O) and release energy.
336. In the reaction $2KClO_3 \xrightarrow{MnO_2} 2KCl + 3O_2$, the role of manganese dioxide (MnO₂) is:
ⓐ. It acts as a reducing agent
ⓑ. It reacts with potassium chloride
ⓒ. It is a product of the reaction
ⓓ. It acts as a catalyst
Correct Answer: It acts as a catalyst
Explanation: Manganese dioxide (MnO₂) acts as a catalyst in this reaction. It speeds up the decomposition of potassium chlorate (KClO₃) into potassium chloride (KCl) and oxygen gas (O₂) without being consumed in the process.
337. Which of the following chemical equations represents a neutralization reaction?
ⓐ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓑ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓒ. $2H_2 + O_2 \rightarrow 2H_2O$
ⓓ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Correct Answer: $NaOH + HCl \rightarrow NaCl + H_2O$
Explanation: A neutralization reaction involves an acid and a base reacting to form a salt and water. In this case, sodium hydroxide (NaOH), a base, reacts with hydrochloric acid (HCl) to form sodium chloride (NaCl), a salt, and water (H₂O).
338. Which of the following is an example of a disproportionation reaction?
ⓐ. $H_2 + Cl_2 \rightarrow 2HCl$
ⓑ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓒ. $2NaCl + F_2 \rightarrow 2NaF + Cl_2$
ⓓ. $2Cl^- + H_2O \rightarrow Cl_2 + 2OH^-$
Correct Answer: $2Cl^- + H_2O \rightarrow Cl_2 + 2OH^-$
Explanation: A disproportionation reaction occurs when a substance is both oxidized and reduced in the same reaction. In this case, chloride ions (Cl⁻) are both oxidized to chlorine gas (Cl₂) and reduced to hydroxide ions (OH⁻) in the presence of water.
339. Which of the following reactions is an example of a precipitation reaction?
ⓐ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓑ. $CaCl_2 + Na_2CO_3 \rightarrow CaCO_3 + 2NaCl$
ⓒ. $H_2 + O_2 \rightarrow H_2O$
ⓓ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
Correct Answer: $CaCl_2 + Na_2CO_3 \rightarrow CaCO_3 + 2NaCl$
Explanation: A precipitation reaction occurs when two soluble salts react to form an insoluble product, known as a precipitate. In this case, calcium carbonate (CaCO₃) is formed as a solid precipitate when calcium chloride (CaCl₂) reacts with sodium carbonate (Na₂CO₃).
340. Which of the following chemical equations represents a redox reaction?
ⓐ. $2H_2O_2 \rightarrow 2H_2O + O_2$
ⓑ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓒ. $CuSO_4 + Zn \rightarrow ZnSO_4 + Cu$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Correct Answer: $2H_2O_2 \rightarrow 2H_2O + O_2$
Explanation: This is a redox reaction because hydrogen peroxide (H₂O₂) undergoes both oxidation (losing electrons to form oxygen gas, O₂) and reduction (gaining electrons to form water, H₂O). Redox reactions involve the transfer of electrons between the reactants, which is the case in this decomposition of hydrogen peroxide.
341. In the reaction $2Na + Cl_2 \rightarrow 2NaCl$, which element is oxidized and which element is reduced?
ⓐ. Sodium is reduced, chlorine is oxidized
ⓑ. Sodium is oxidized, chlorine is reduced
ⓒ. Both sodium and chlorine are oxidized
ⓓ. Both sodium and chlorine are reduced
Correct Answer: Sodium is oxidized, chlorine is reduced
Explanation: In this reaction, sodium (Na) loses an electron to form $Na^+$, so it is oxidized. Chlorine (Cl₂) gains electrons to form $Cl^-$, so it is reduced. This reaction is a classic example of a redox reaction, where sodium is the reducing agent and chlorine is the oxidizing agent.
342. Which of the following reactions is an example of a combustion reaction?
ⓐ. $C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O$
ⓑ. $NaOH + HCl \rightarrow NaCl + H_2O$
ⓒ. $2Na + Cl_2 \rightarrow 2NaCl$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Correct Answer: $C_2H_5OH + 3O_2 \rightarrow 2CO_2 + 3H_2O$
Explanation: A combustion reaction occurs when a substance reacts with oxygen to produce energy, typically in the form of heat and light. In this reaction, ethanol (C₂H₅OH) reacts with oxygen to produce carbon dioxide (CO₂) and water (H₂O), releasing energy. This is a classic example of a combustion reaction.
343. Which of the following reactions is an example of a double displacement reaction?
ⓐ. $2Na + Cl_2 \rightarrow 2NaCl$
ⓑ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓒ. $H_2 + O_2 \rightarrow H_2O$
ⓓ. $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$
Correct Answer: $NaCl + AgNO_3 \rightarrow NaNO_3 + AgCl$
Explanation: A double displacement reaction occurs when the cations and anions of two ionic compounds exchange places to form new compounds. In this case, sodium chloride (NaCl) reacts with silver nitrate (AgNO₃) to form sodium nitrate (NaNO₃) and silver chloride (AgCl), a precipitate.
Welcome to Class 11 Chemistry MCQs – Chapter 9: Hydrogen (Part 4). This final part wraps up the chapter with 43 MCQs focusing on advanced hydrogen reactions and its role in modern applications. Perfect for quick revision before exams!
- 👉 Total in chapter: 343 MCQs
- 👉 This page contains: 43 solved MCQs
- 👉 Perfect for last-minute revision before exams