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301. Which of the following is the primary role of sodium (Na⁺) and potassium (K⁺) ions in nerve impulse transmission?
ⓐ. They help in the formation of neurotransmitters
ⓑ. They provide energy for the transmission of nerve signals
ⓒ. They facilitate the absorption of glucose in nerve cells
ⓓ. They generate electrical signals by moving across the nerve membrane
Correct Answer: They generate electrical signals by moving across the nerve membrane
Explanation: Sodium (Na⁺) and potassium (K⁺) ions play a crucial role in nerve impulse transmission by moving across the nerve membrane during the action potential. The movement of these ions creates an electrical signal that allows nerve impulses to travel along neurons.
302. What is the mechanism by which sodium (Na⁺) and potassium (K⁺) ions maintain osmotic balance in the body?
ⓐ. Through active transport via the sodium-potassium pump (Na⁺/K⁺ pump)
ⓑ. By forming ionic bonds with water molecules
ⓒ. By balancing the pH level in body fluids
ⓓ. Through passive diffusion across cell membranes
Correct Answer: Through active transport via the sodium-potassium pump (Na⁺/K⁺ pump)
Explanation: Sodium (Na⁺) and potassium (K⁺) ions maintain osmotic balance by using the sodium-potassium pump (Na⁺/K⁺ pump), an active transport mechanism. This pump moves three sodium ions out of the cell and two potassium ions into the cell, helping to maintain the proper ionic balance and osmotic pressure inside cells.
303. How does the sodium-potassium pump (Na⁺/K⁺ pump) contribute to nerve function?
ⓐ. It helps in the release of neurotransmitters
ⓑ. It maintains the resting membrane potential and facilitates action potentials
ⓒ. It stores calcium ions for synaptic release
ⓓ. It directly synthesizes ATP for energy in neurons
Correct Answer: It maintains the resting membrane potential and facilitates action potentials
Explanation: The sodium-potassium pump (Na⁺/K⁺ pump) is essential for maintaining the resting membrane potential in neurons by ensuring a higher concentration of sodium (Na⁺) outside the cell and potassium (K⁺) inside the cell. This ionic gradient allows for the rapid depolarization and repolarization of the membrane during action potentials.
304. Which of the following is true about the movement of sodium (Na⁺) and potassium (K⁺) ions during an action potential in a neuron?
ⓐ. Sodium ions move into the cell, and potassium ions move out of the cell
ⓑ. Both sodium and potassium ions move into the cell
ⓒ. Sodium ions move out of the cell, and potassium ions move into the cell
ⓓ. Both sodium and potassium ions move out of the cell
Correct Answer: Sodium ions move into the cell, and potassium ions move out of the cell
Explanation: During an action potential, sodium ions (Na⁺) move into the neuron, causing depolarization, while potassium ions (K⁺) move out of the neuron, leading to repolarization. This movement of ions is essential for the transmission of nerve impulses along neurons.
305. What is the primary function of potassium (K⁺) in nerve impulse transmission?
ⓐ. To maintain the concentration of glucose in neurons
ⓑ. To generate the electrical signal for synaptic transmission
ⓒ. To establish the resting potential and restore the cell after depolarization
ⓓ. To bind with neurotransmitters and facilitate their release
Correct Answer: To establish the resting potential and restore the cell after depolarization
Explanation: Potassium (K⁺) plays a critical role in establishing the resting membrane potential of neurons and restoring the cell to its resting state after depolarization. Potassium ions move out of the cell during repolarization, helping to reestablish the negative charge inside the neuron.
306. How does the movement of sodium (Na⁺) and potassium (K⁺) ions across the cell membrane affect osmotic balance in the body?
ⓐ. By creating an ionic gradient that helps control fluid distribution across cell membranes
ⓑ. By regulating the concentration of glucose inside the cell
ⓒ. By maintaining high levels of calcium inside the cell
ⓓ. By preventing the diffusion of water into the cell
Correct Answer: By creating an ionic gradient that helps control fluid distribution across cell membranes
Explanation: The movement of sodium (Na⁺) and potassium (K⁺) ions across the cell membrane creates an ionic gradient that is essential for osmotic balance. This gradient influences fluid distribution between the intracellular and extracellular environments, maintaining proper hydration and volume inside cells.
307. Which of the following best describes the role of sodium (Na⁺) in nerve impulse transmission?
ⓐ. Sodium ions help transmit the action potential by moving across the cell membrane
ⓑ. Sodium ions are involved in the release of neurotransmitters from the synapse
ⓒ. Sodium ions regulate the reabsorption of water in the kidneys
ⓓ. Sodium ions help in the breakdown of ATP for energy production
Correct Answer: Sodium ions help transmit the action potential by moving across the cell membrane
Explanation: Sodium (Na⁺) ions play a key role in nerve impulse transmission by moving into the cell during depolarization, generating the action potential. This influx of sodium ions is essential for the propagation of electrical signals along the neuron.
308. Which of the following ions is primarily involved in generating the resting membrane potential of neurons?
ⓐ. Sodium (Na⁺)
ⓑ. Calcium (Ca²⁺)
ⓒ. Chloride (Cl⁻)
ⓓ. Potassium (K⁺)
Correct Answer: Potassium (K⁺)
Explanation: Potassium (K⁺) ions are primarily responsible for generating the resting membrane potential of neurons. The sodium-potassium pump maintains a higher concentration of potassium inside the cell and sodium outside the cell, which is essential for maintaining the negative charge inside the neuron at rest.
309. What happens to the concentration of sodium (Na⁺) and potassium (K⁺) ions during the depolarization of a neuron?
ⓐ. Sodium concentration decreases inside the cell, and potassium concentration increases
ⓑ. Both sodium and potassium concentrations increase inside the cell
ⓒ. Sodium concentration increases inside the cell, and potassium concentration decreases
ⓓ. Both sodium and potassium concentrations decrease inside the cell
Correct Answer: Sodium concentration increases inside the cell, and potassium concentration decreases
Explanation: During depolarization, sodium (Na⁺) ions move rapidly into the neuron, causing the inside of the cell to become more positive. At the same time, potassium (K⁺) ions remain inside the cell, but they are not significantly involved in this phase of the action potential. Potassium ions move out during the repolarization phase.
310. How does potassium (K⁺) affect the function of the sodium-potassium pump (Na⁺/K⁺ pump)?
ⓐ. Potassium helps the pump transport sodium ions into the cell
ⓑ. Potassium inhibits the pump from operating
ⓒ. Potassium binds with sodium to form a complex that moves across the membrane
ⓓ. Potassium is transported by the pump into the cell while sodium is removed
Correct Answer: Potassium is transported by the pump into the cell while sodium is removed
Explanation: The sodium-potassium pump (Na⁺/K⁺ pump) actively transports sodium ions (Na⁺) out of the cell and potassium ions (K⁺) into the cell. This pump helps maintain the necessary ionic gradients for proper nerve function and osmotic balance. Three sodium ions are pumped out for every two potassium ions pumped in.
311. What is the primary role of magnesium (Mg²⁺) in chlorophyll?
ⓐ. It helps in the absorption of light for photosynthesis
ⓑ. It acts as a catalyst for the breakdown of glucose
ⓒ. It binds with carbon dioxide to form glucose
ⓓ. It stabilizes the plant cell wall during photosynthesis
Correct Answer: It helps in the absorption of light for photosynthesis
Explanation: Magnesium (Mg²⁺) is the central metal ion in the chlorophyll molecule, and it plays a crucial role in photosynthesis by helping to absorb light. The magnesium ion allows chlorophyll to absorb photons effectively and transfer energy during the light-dependent reactions.
312. How does magnesium (Mg²⁺) contribute to enzyme activation?
ⓐ. It inhibits the activity of enzymes
ⓑ. It binds with enzymes to form an inactive complex
ⓒ. It activates enzymes by forming a stable enzyme-substrate complex
ⓓ. It degrades the enzyme-substrate complex to release energy
Correct Answer: It activates enzymes by forming a stable enzyme-substrate complex
Explanation: Magnesium (Mg²⁺) acts as a cofactor for many enzymes, activating them by forming a stable enzyme-substrate complex. This is especially important in reactions involving ATP, as magnesium is required for the activation of ATPase and other ATP-dependent enzymes.
313. Which of the following enzymes is activated by magnesium (Mg²⁺)?
ⓐ. Amylase
ⓑ. DNA polymerase
ⓒ. Lipase
ⓓ. Phosphorylase
Correct Answer: DNA polymerase
Explanation: Magnesium (Mg²⁺) is an essential cofactor for DNA polymerase, an enzyme that plays a crucial role in DNA replication. The magnesium ion is required for the enzyme to catalyze the synthesis of DNA by stabilizing the phosphate groups during the process.
314. In photosynthesis, what is the role of magnesium (Mg²⁺) in the chlorophyll molecule?
ⓐ. It helps transfer electrons to the electron transport chain
ⓑ. It stabilizes the thylakoid membrane
ⓒ. It helps synthesize glucose during the Calvin cycle
ⓓ. It helps in the absorption of sunlight by chlorophyll
Correct Answer: It helps in the absorption of sunlight by chlorophyll
Explanation: Magnesium (Mg²⁺) in the center of the chlorophyll molecule helps absorb light and initiate the light-dependent reactions of photosynthesis. This allows plants to capture energy from sunlight and convert it into chemical energy in the form of ATP and NADPH.
315. Which of the following statements about magnesium (Mg²⁺) and chlorophyll is true?
ⓐ. Magnesium is essential for the synthesis of chlorophyll in plants
ⓑ. Magnesium inhibits chlorophyll synthesis
ⓒ. Magnesium is not required for chlorophyll function in plants
ⓓ. Magnesium binds to oxygen molecules in chlorophyll
Correct Answer: Magnesium is essential for the synthesis of chlorophyll in plants
Explanation: Magnesium (Mg²⁺) is a key component in the synthesis of chlorophyll. Without magnesium, chlorophyll cannot form, which would inhibit photosynthesis in plants. It is the central metal ion in the porphyrin ring structure of chlorophyll.
316. What happens when magnesium (Mg²⁺) deficiency occurs in plants?
ⓐ. It enhances photosynthetic efficiency
ⓑ. It accelerates cell division
ⓒ. It causes the plant to produce excess chlorophyll
ⓓ. It leads to yellowing of leaves (chlorosis)
Correct Answer: It leads to yellowing of leaves (chlorosis)
Explanation: Magnesium deficiency in plants leads to chlorosis, which is the yellowing of leaves. Magnesium is essential for chlorophyll production, and without sufficient magnesium, plants cannot produce enough chlorophyll, affecting their ability to perform photosynthesis.
317. What is the role of magnesium (Mg²⁺) in the activation of ATP-dependent enzymes?
ⓐ. It inhibits the enzyme activity by binding to ATP
ⓑ. It enhances the enzyme activity by stabilizing ATP
ⓒ. It breaks down ATP to release energy
ⓓ. It forms a stable bond with ADP
Correct Answer: It enhances the enzyme activity by stabilizing ATP
Explanation: Magnesium (Mg²⁺) enhances the activity of ATP-dependent enzymes by stabilizing the negative charges on ATP. This stabilizing effect allows the enzyme to effectively use ATP as an energy source for biochemical reactions.
318. In what form is magnesium (Mg²⁺) typically found in chlorophyll?
ⓐ. As a complex with chlorophyll a
ⓑ. As a free ion in the stroma
ⓒ. As a part of the electron transport chain
ⓓ. As a cofactor for ribulose bisphosphate carboxylase
Correct Answer: As a complex with chlorophyll a
Explanation: Magnesium (Mg²⁺) is centrally located in the porphyrin ring of chlorophyll a, where it plays an essential role in the absorption of light and the initiation of the photosynthetic process.
319. Which of the following physiological processes is magnesium (Mg²⁺) involved in?
ⓐ. Photosynthesis and enzyme activation
ⓑ. Protein synthesis and muscle contraction
ⓒ. DNA replication and cell division
ⓓ. Oxygen transport and blood clotting
Correct Answer: Photosynthesis and enzyme activation
Explanation: Magnesium (Mg²⁺) plays key roles in both photosynthesis (as part of chlorophyll) and enzyme activation. It activates several enzymes involved in ATP metabolism and helps plants carry out essential functions like energy production and growth.
320. How does magnesium (Mg²⁺) assist in enzyme activation in biochemical reactions?
ⓐ. By providing energy directly to the enzyme
ⓑ. By breaking down substrates into simpler molecules
ⓒ. By binding to the enzyme, altering its shape for catalysis
ⓓ. By stabilizing enzyme-substrate complexes during reactions
Correct Answer: By binding to the enzyme, altering its shape for catalysis
Explanation: Magnesium (Mg²⁺) assists in enzyme activation by binding to the enzyme and altering its conformation, enabling it to bind more efficiently with substrates. This helps in catalyzing biochemical reactions, especially those involving ATP and other phosphate-containing molecules.
321. Which of the following is the primary role of calcium (Ca²⁺) in bones and teeth?
ⓐ. To provide flexibility
ⓑ. To assist in energy production
ⓒ. To provide structural support and strength
ⓓ. To regulate blood pressure
Correct Answer: To provide structural support and strength
Explanation: Calcium (Ca²⁺) plays a crucial role in the formation of bones and teeth by contributing to their structure and strength. Calcium ions are deposited in bone tissue, forming hydroxyapatite crystals that give bones their rigidity and teeth their hardness.
322. How does calcium (Ca²⁺) contribute to blood clotting?
ⓐ. By promoting the breakdown of fibrin
ⓑ. By activating clotting factors like prothrombin
ⓒ. By increasing the viscosity of blood
ⓓ. By dissolving blood clots
Correct Answer: By activating clotting factors like prothrombin
Explanation: Calcium (Ca²⁺) plays a vital role in the blood clotting process by activating several clotting factors, including prothrombin. Calcium ions are essential in the coagulation cascade, helping to form fibrin threads that trap blood cells and stop bleeding.
323. Which of the following is the mineral form of calcium found in bones and teeth?
ⓐ. Calcium sulfate (CaSO₄)
ⓑ. Calcium carbonate (CaCO₃)
ⓒ. Calcium phosphate (Ca₃(PO₄)₂)
ⓓ. Calcium hydroxide (Ca(OH)₂)
Correct Answer: Calcium phosphate (Ca₃(PO₄)₂)
Explanation: Calcium phosphate ($Ca_3(PO_4)_2$) is the primary mineral form of calcium found in bones and teeth. It provides strength and rigidity to bone tissue and hardness to teeth. Hydroxyapatite, a crystalline form of calcium phosphate, is the main component of bone and tooth mineralization.
324. What is the role of calcium (Ca²⁺) in muscle contraction?
ⓐ. It facilitates the breakdown of ATP for energy
ⓑ. It binds to troponin, allowing actin and myosin to interact
ⓒ. It enhances the activity of enzymes involved in glycolysis
ⓓ. It regulates the flow of sodium ions in and out of cells
Correct Answer: It binds to troponin, allowing actin and myosin to interact
Explanation: Calcium (Ca²⁺) plays a key role in muscle contraction by binding to the troponin complex on the actin filament. This binding causes a conformational change that exposes binding sites on actin, allowing myosin to attach and produce contraction.
325. What is the effect of calcium (Ca²⁺) deficiency on bones and teeth?
ⓐ. Softening of bones and weakening of teeth
ⓑ. Increased risk of blood clots
ⓒ. Improved strength and rigidity
ⓓ. Excessive bone growth
Correct Answer: Softening of bones and weakening of teeth
Explanation: Calcium deficiency leads to conditions such as osteomalacia (softening of bones) and weak, brittle teeth. Calcium is essential for maintaining the hardness and strength of bones and teeth, and without sufficient calcium, these structures lose their mineral content.
326. Which of the following hormones regulates calcium levels in the blood?
ⓐ. Insulin
ⓑ. Glucagon
ⓒ. Parathyroid hormone (PTH)
ⓓ. Thyroid-stimulating hormone (TSH)
Correct Answer: Parathyroid hormone (PTH)
Explanation: Parathyroid hormone (PTH) regulates calcium levels in the blood by increasing calcium levels when they are too low. It does so by promoting calcium release from bones, increasing calcium reabsorption by the kidneys, and activating vitamin D, which enhances calcium absorption from the intestines.
327. Which of the following is a condition caused by calcium (Ca²⁺) deficiency?
ⓐ. Rickets
ⓑ. Scurvy
ⓒ. Hemophilia
ⓓ. Anemia
Correct Answer: Rickets
Explanation: Rickets is a condition caused by calcium (Ca²⁺) deficiency in children, leading to soft, weak bones that can deform under the weight of the body. In adults, calcium deficiency can cause osteomalacia, which is similar but occurs in fully developed bones.
328. How does calcium (Ca²⁺) contribute to the regulation of blood pressure?
ⓐ. By constricting blood vessels
ⓑ. By enhancing the effects of adrenaline
ⓒ. By promoting the absorption of sodium ions
ⓓ. By regulating the contraction and relaxation of blood vessel muscles
Correct Answer: By regulating the contraction and relaxation of blood vessel muscles
Explanation: Calcium (Ca²⁺) helps regulate blood pressure by controlling the contraction and relaxation of smooth muscle in blood vessels. Calcium ions promote vasoconstriction (narrowing of blood vessels) and vasodilation (widening of blood vessels), which influences blood pressure.
329. Which of the following is a primary source of calcium in the diet?
ⓐ. Red meat
ⓑ. Whole grains
ⓒ. Leafy green vegetables
ⓓ. Dairy products
Correct Answer: Dairy products
Explanation: Dairy products, such as milk, cheese, and yogurt, are the primary dietary sources of calcium. These foods provide high amounts of calcium, which is essential for bone and teeth health, as well as for muscle function and blood clotting.
330. How does calcium (Ca²⁺) play a role in enzyme activation?
ⓐ. By inhibiting the enzyme activity
ⓑ. By providing the energy required for enzyme catalysis
ⓒ. By binding to enzymes to alter their shape and activate them
ⓓ. By breaking down the enzyme-substrate complex
Correct Answer: By binding to enzymes to alter their shape and activate them
Explanation: Calcium (Ca²⁺) activates enzymes by binding to specific sites on the enzyme, altering its shape and enabling it to perform its function. Calcium ions are required for the activity of many enzymes involved in biochemical processes such as blood clotting and muscle contraction.
331. What is the product when calcium carbide (CaC₂) reacts with water?
ⓐ. Calcium hydroxide (Ca(OH)₂) and carbon dioxide (CO₂)
ⓑ. Calcium oxide (CaO) and acetylene gas (C₂H₂)
ⓒ. Calcium carbide (CaC₂) and hydrogen gas (H₂)
ⓓ. Calcium carbonate (CaCO₃) and hydrogen gas (H₂)
Correct Answer: Calcium hydroxide (Ca(OH)₂) and carbon dioxide (CO₂)
Explanation: When calcium carbide (CaC₂) reacts with water, it produces calcium hydroxide (Ca(OH)₂) and acetylene gas (C₂H₂). The reaction is $CaC_2 + 2H_2O \rightarrow Ca(OH)_2 + C_2H_2$.
332. What is the product of the reaction between sodium (Na) and water?
ⓐ. Sodium hydroxide (NaOH) and hydrogen gas (H₂)
ⓑ. Sodium carbonate (Na₂CO₃) and oxygen gas (O₂)
ⓒ. Sodium bicarbonate (NaHCO₃) and carbon dioxide (CO₂)
ⓓ. Sodium chloride (NaCl) and oxygen gas (O₂)
Correct Answer: Sodium hydroxide (NaOH) and hydrogen gas (H₂)
Explanation: Sodium (Na) reacts with water to form sodium hydroxide (NaOH) and hydrogen gas (H₂) in an exothermic reaction. The equation is:
$2Na + 2H_2O \rightarrow 2NaOH + H_2$.
333. When magnesium (Mg) reacts with hydrochloric acid (HCl), which of the following is the correct chemical equation?
ⓐ. $Mg + HCl \rightarrow MgCl_2 + H_2$
ⓑ. $Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$
ⓒ. $Mg + 2H_2O \rightarrow MgO + H_2$
ⓓ. $Mg + 2HCl \rightarrow MgCl_2 + H_2$
Correct Answer: $Mg + 2HCl \rightarrow MgCl_2 + H_2$
Explanation: Magnesium reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl₂) and hydrogen gas (H₂). The reaction is:
$Mg + 2HCl \rightarrow MgCl_2 + H_2$.
334. What is the balanced chemical equation for the reaction of calcium oxide (CaO) with carbon dioxide (CO₂)?
ⓐ. $CaO + CO_2 \rightarrow CaCO_2$
ⓑ. $CaO + CO_2 \rightarrow CaCO_3$
ⓒ. $CaO + CO_2 \rightarrow CaO_2 + CO$
ⓓ. $CaO + 2CO_2 \rightarrow CaCO_3$
Correct Answer: $CaO + CO_2 \rightarrow CaCO_3$
Explanation: When calcium oxide (CaO) reacts with carbon dioxide (CO₂), it forms calcium carbonate (CaCO₃), which is commonly known as lime in the solid form. The balanced equation is:
$CaO + CO_2 \rightarrow CaCO_3$.
335. Which of the following reactions correctly represents the decomposition of sodium bicarbonate (NaHCO₃)?
ⓐ. $2NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
ⓑ. $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2$
ⓒ. $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO + H_2O$
ⓓ. $NaHCO_3 \xrightarrow{heat} NaOH + CO_2$
Correct Answer: $2NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
Explanation: Sodium bicarbonate (NaHCO₃) decomposes upon heating to produce sodium carbonate (Na₂CO₃), carbon dioxide (CO₂), and water (H₂O). The balanced equation is:
$2NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$.
336. What is the correct chemical equation for the reaction between sodium hydroxide (NaOH) and carbon dioxide (CO₂)?
ⓐ. $NaOH + CO_2 \rightarrow NaHCO_3$
ⓑ. $NaOH + CO_2 \rightarrow NaCO_3 + H_2O$
ⓒ. $NaOH + CO_2 \rightarrow NaCO_3$
ⓓ. $NaOH + CO_2 \rightarrow NaHCO_3 + H_2O$
Correct Answer: $NaOH + CO_2 \rightarrow NaHCO_3$
Explanation: Sodium hydroxide (NaOH) reacts with carbon dioxide (CO₂) to form sodium bicarbonate (NaHCO₃). This reaction is commonly used in the preparation of soda in industrial processes. The balanced equation is:
$NaOH + CO_2 \rightarrow NaHCO_3$.
337. What happens when calcium hydroxide (Ca(OH)₂) reacts with sulfuric acid (H₂SO₄)?
ⓐ. It forms calcium chloride (CaCl₂) and water
ⓑ. It forms calcium carbonate (CaCO₃) and water
ⓒ. It forms calcium sulfate (CaSO₄) and water
ⓓ. It forms calcium phosphate (Ca₃(PO₄)₂) and water
Correct Answer: It forms calcium sulfate (CaSO₄) and water
Explanation: Calcium hydroxide (Ca(OH)₂) reacts with sulfuric acid (H₂SO₄) to form calcium sulfate (CaSO₄) and water. The reaction is:
$Ca(OH)_2 + H_2SO_4 \rightarrow CaSO_4 + 2H_2O$.
338. What is the correct chemical equation for the reaction of magnesium oxide (MgO) with water?
ⓐ. $MgO + H_2O \rightarrow Mg(OH)_3$
ⓑ. $MgO + H_2O \rightarrow MgO_2 + H_2$
ⓒ. $MgO + H_2O \rightarrow Mg_2O_3$
ⓓ. $MgO + H_2O \rightarrow Mg(OH)_2$
Correct Answer: $MgO + H_2O \rightarrow Mg(OH)_2$
Explanation: Magnesium oxide (MgO) reacts with water to form magnesium hydroxide (Mg(OH)₂). This is a typical reaction for magnesium oxide, which forms a slightly alkaline solution. The equation is:
$MgO + H_2O \rightarrow Mg(OH)_2$.
339. Which of the following reactions occurs when calcium hydroxide (Ca(OH)₂) reacts with carbon dioxide (CO₂)?
ⓐ. $Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$
ⓑ. $Ca(OH)_2 + CO_2 \rightarrow CaCO_3$
ⓒ. $Ca(OH)_2 + CO_2 \rightarrow Ca(OH)_2 + CO_2$
ⓓ. $Ca(OH)_2 + CO_2 \rightarrow Ca(HCO_3)_2$
Correct Answer: $Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$
Explanation: When calcium hydroxide (Ca(OH)₂) reacts with carbon dioxide (CO₂), it forms calcium carbonate (CaCO₃) and water. This reaction is important in the formation of limestone and in processes like carbon capture. The equation is:
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$.
340. What is the result when sodium carbonate (Na₂CO₃) reacts with hydrochloric acid (HCl)?
ⓐ. Sodium hydroxide (NaOH) and carbon dioxide (CO₂)
ⓑ. Sodium bicarbonate (NaHCO₃) and water (H₂O)
ⓒ. Sodium chloride (NaCl) and carbon dioxide (CO₂)
ⓓ. Sodium chloride (NaCl) and water (H₂O)
Correct Answer: Sodium chloride (NaCl) and carbon dioxide (CO₂)
Explanation: Sodium carbonate (Na₂CO₃) reacts with hydrochloric acid (HCl) to form sodium chloride (NaCl), water (H₂O), and carbon dioxide (CO₂). The equation is:
$Na_2CO_3 + 2HCl \rightarrow 2NaCl + H_2O + CO_2$.
341. What is the product formed when calcium oxide (CaO) reacts with water?
ⓐ. Calcium sulfate (CaSO₄)
ⓑ. Calcium carbonate (CaCO₃)
ⓒ. Calcium hydroxide (Ca(OH)₂)
ⓓ. Calcium phosphate (Ca₃(PO₄)₂)
Correct Answer: Calcium hydroxide (Ca(OH)₂)
Explanation: When calcium oxide (CaO), also known as quicklime, reacts with water, it forms calcium hydroxide (Ca(OH)₂), also known as slaked lime. This is an exothermic reaction that releases heat:
$CaO + H_2O \rightarrow Ca(OH)_2$.
342. Which of the following reactions demonstrates the decomposition of calcium carbonate (CaCO₃) upon heating?
ⓐ. $CaCO_3 \xrightarrow{heat} CaO + CO_2$
ⓑ. $CaCO_3 \xrightarrow{heat} CaCO_2$
ⓒ. $CaCO_3 \xrightarrow{heat} Ca(OH)_2 + CO_2$
ⓓ. $CaCO_3 \xrightarrow{heat} CaO + C_2O_4$
Correct Answer: $CaCO_3 \xrightarrow{heat} CaO + CO_2$
Explanation: When calcium carbonate (CaCO₃) is heated, it undergoes decomposition to form calcium oxide (CaO) and carbon dioxide (CO₂). This reaction is a key part of the lime production process, where calcium oxide is produced:
$CaCO_3 \xrightarrow{heat} CaO + CO_2$.
343. Which of the following is the correct reaction when sodium bicarbonate (NaHCO₃) decomposes upon heating?
ⓐ. $NaHCO_3 \xrightarrow{heat} Na_2O + CO_2 + H_2O$
ⓑ. $NaHCO_3 \xrightarrow{heat} NaOH + CO_2$
ⓒ. $NaHCO_3 \xrightarrow{heat} NaCl + CO_2 + H_2O$
ⓓ. $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
Correct Answer: $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
Explanation: When sodium bicarbonate (NaHCO₃) is heated, it decomposes into sodium carbonate (Na₂CO₃), carbon dioxide (CO₂), and water (H₂O). This reaction is commonly used in baking, where carbon dioxide is released to help dough rise:
$2NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$.
344. What happens when sodium chloride (NaCl) reacts with concentrated sulfuric acid (H₂SO₄)?
ⓐ. Sodium bisulfate (NaHSO₄) and hydrogen chloride (HCl)
ⓑ. Sodium sulfate (Na₂SO₄) and hydrogen chloride (HCl)
ⓒ. Sodium chloride (NaCl) and sulfur dioxide (SO₂)
ⓓ. Sodium sulfate (Na₂SO₄) and sulfur dioxide (SO₂)
Correct Answer: Sodium sulfate (Na₂SO₄) and hydrogen chloride (HCl)
Explanation: When sodium chloride (NaCl) reacts with concentrated sulfuric acid (H₂SO₄), it produces sodium sulfate (Na₂SO₄) and hydrogen chloride (HCl). The reaction is:
$2NaCl + H_2SO_4 \rightarrow Na_2SO_4 + 2HCl$.
This is a key reaction in the production of hydrogen chloride gas.
345. Which of the following equations correctly represents the reaction between magnesium (Mg) and hydrochloric acid (HCl)?
ⓐ. $Mg + HCl \rightarrow MgCl + H_2$
ⓑ. $Mg + 2H_2O \rightarrow Mg(OH)_2 + H_2$
ⓒ. $Mg + 2HCl \rightarrow MgCl_2 + H_2$
ⓓ. $Mg + 2H_2O \rightarrow MgO + H_2$
Correct Answer: $Mg + 2HCl \rightarrow MgCl_2 + H_2$
Explanation: Magnesium (Mg) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl₂) and hydrogen gas (H₂). This reaction is an example of a metal-acid reaction where the metal displaces hydrogen ions from the acid:
$Mg + 2HCl \rightarrow MgCl_2 + H_2$.
346. What is the product of the reaction between calcium hydroxide (Ca(OH)₂) and carbon dioxide (CO₂)?
ⓐ. Calcium bicarbonate (Ca(HCO₃)₂)
ⓑ. Calcium carbonate (CaCO₃)
ⓒ. Calcium oxide (CaO)
ⓓ. Calcium sulfate (CaSO₄)
Correct Answer: Calcium carbonate (CaCO₃)
Explanation: When calcium hydroxide (Ca(OH)₂) reacts with carbon dioxide (CO₂), it forms calcium carbonate (CaCO₃), which is a white precipitate. This reaction is commonly used in water treatment and is the basis of limestone formation:
$Ca(OH)_2 + CO_2 \rightarrow CaCO_3 + H_2O$.
347. What is the correct chemical equation for the reaction between sodium hydroxide (NaOH) and sulfuric acid (H₂SO₄)?
ⓐ. $NaOH + H_2SO_4 \rightarrow NaHSO_4 + H_2O$
ⓑ. $NaOH + H_2SO_4 \rightarrow NaSO_4 + H_2O$
ⓒ. $NaOH + H_2SO_4 \rightarrow Na_2SO_4 + H_2O$
ⓓ. $NaOH + H_2SO_4 \rightarrow Na_2SO_3 + H_2O$
Correct Answer: $NaOH + H_2SO_4 \rightarrow NaHSO_4 + H_2O$
Explanation: When sodium hydroxide (NaOH) reacts with sulfuric acid (H₂SO₄), it produces sodium bisulfate (NaHSO₄) and water (H₂O). The reaction is:
$NaOH + H_2SO_4 \rightarrow NaHSO_4 + H_2O$.
348. When calcium oxide (CaO) is added to water, what is the product formed?
ⓐ. Calcium phosphide (Ca₃P₂)
ⓑ. Calcium carbonate (CaCO₃)
ⓒ. Calcium sulfate (CaSO₄)
ⓓ. Calcium hydroxide (Ca(OH)₂)
Correct Answer: Calcium hydroxide (Ca(OH)₂)
Explanation: When calcium oxide (CaO) reacts with water, it forms calcium hydroxide (Ca(OH)₂), also known as slaked lime. This is a highly exothermic reaction, meaning it releases heat:
$CaO + H_2O \rightarrow Ca(OH)_2$.
349. What happens when calcium carbonate (CaCO₃) is heated in the presence of excess carbon dioxide (CO₂)?
ⓐ. Calcium carbonate (CaCO₃) decomposes to form calcium oxide (CaO)
ⓑ. Calcium carbonate (CaCO₃) reacts with CO₂ to form calcium bicarbonate (Ca(HCO₃)₂)
ⓒ. Calcium carbonate (CaCO₃) reacts with CO₂ to form calcium hydroxide (Ca(OH)₂)
ⓓ. Calcium carbonate (CaCO₃) forms calcium phosphate (Ca₃(PO₄)₂)
Correct Answer: Calcium carbonate (CaCO₃) reacts with CO₂ to form calcium bicarbonate (Ca(HCO₃)₂)
Explanation: Calcium carbonate (CaCO₃) reacts with excess carbon dioxide (CO₂) to form calcium bicarbonate (Ca(HCO₃)₂), which is soluble in water. This reaction is important in the formation of temporary hardness in water:
$CaCO_3 + CO_2 + H_2O \rightarrow Ca(HCO_3)_2$.
350. Which of the following is the correct equation for the formation of calcium sulfate (CaSO₄) from calcium oxide (CaO) and sulfur trioxide (SO₃)?
ⓐ. $CaO + SO_3 \rightarrow CaSO_4$
ⓑ. $CaO + SO_3 \rightarrow CaSO_3$
ⓒ. $CaSO_4 + H_2O \rightarrow CaO + SO_3$
ⓓ. $CaSO_4 + CO_2 \rightarrow CaCO_3 + SO_2$
Correct Answer: $CaO + SO_3 \rightarrow CaSO_4$
Explanation: When calcium oxide (CaO) reacts with sulfur trioxide (SO₃), it forms calcium sulfate (CaSO₄). This reaction is part of the production of sulfuric acid and other industrial processes involving sulfur compounds:
$CaO + SO_3 \rightarrow CaSO_4$.
351. What is the trend of solubility for the sulfates of alkaline earth metals (Group 2) as we move down the group?
ⓐ. Solubility increases significantly
ⓑ. Solubility decreases significantly
ⓒ. Solubility remains almost constant
ⓓ. Solubility increases, then decreases
Correct Answer: Solubility decreases significantly
Explanation: The solubility of Group 2 sulfates decreases significantly as we move down the group; Beryllium sulfate ($BeSO_4$) and Magnesium sulfate ($MgSO_4$) are quite soluble, while Calcium sulfate ($CaSO_4$) is sparingly soluble, and Strontium ($SrSO_4$) and Barium sulfates ($BaSO_4$) are virtually insoluble.
352. What is the primary product when calcium hydroxide (Ca(OH)₂) reacts with sulfuric acid (H₂SO₄)?
ⓐ. Calcium bisulfate (Ca(HSO₄)₂)
ⓑ. Calcium sulfate (CaSO₄)
ⓒ. Calcium carbonate (CaCO₃)
ⓓ. Calcium phosphate (Ca₃(PO₄)₂)
Correct Answer: Calcium sulfate (CaSO₄)
Explanation: When calcium hydroxide (Ca(OH)₂) reacts with sulfuric acid (H₂SO₄), it forms calcium sulfate (CaSO₄) and water (H₂O). Calcium sulfate is commonly found as gypsum and is used in various applications, including in the construction industry and in agriculture as a soil conditioner. The reaction is:
$Ca(OH)_2 + H_2SO_4 \rightarrow CaSO_4 + 2H_2O$.
353. Which of the following reactions demonstrates the decomposition of sodium bicarbonate (NaHCO₃)?
ⓐ. $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
ⓑ. $NaHCO_3 \xrightarrow{heat} NaOH + CO_2$
ⓒ. $NaHCO_3 \xrightarrow{heat} NaCl + CO_2 + H_2O$
ⓓ. $NaHCO_3 \xrightarrow{heat} Na_2O + CO_2 + H_2O$
Correct Answer: $NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$
Explanation: Sodium bicarbonate (NaHCO₃), when heated, decomposes into sodium carbonate (Na₂CO₃), carbon dioxide (CO₂), and water (H₂O). This reaction is an important process in baking, where the released CO₂ helps the dough rise. The balanced equation is:
$2NaHCO_3 \xrightarrow{heat} Na_2CO_3 + CO_2 + H_2O$.
354. What happens when magnesium (Mg) reacts with excess oxygen (O₂)?
ⓐ. Magnesium sulfate (MgSO₄) is formed
ⓑ. Magnesium hydroxide (Mg(OH)₂) is formed
ⓒ. Magnesium peroxide (MgO₂) is formed
ⓓ. Magnesium oxide (MgO) is formed
Correct Answer: Magnesium oxide (MgO) is formed
Explanation: When magnesium (Mg) reacts with excess oxygen (O₂), magnesium oxide (MgO) is formed. This is an exothermic reaction where magnesium burns with a bright white flame in the presence of oxygen. Magnesium oxide is a white solid that is highly basic in nature. The reaction is:
$2Mg + O_2 \rightarrow 2MgO$.
355. Which of the following equations represents the reaction of sulfur dioxide (SO₂) with oxygen (O₂) in the contact process for the production of sulfur trioxide (SO₃)?
ⓐ. $SO_2 + H₂O \rightarrow H₂SO₄$
ⓑ. $SO_2 + O_2 \rightarrow SO_3$
ⓒ. $2SO_2 + O_2 \rightarrow 2SO_3$
ⓓ. $2SO_3 + H₂O \rightarrow H₂SO₄$
Correct Answer: $2SO_2 + O_2 \rightarrow 2SO_3$
Explanation: In the contact process, sulfur dioxide (SO₂) reacts with oxygen (O₂) in the presence of a catalyst (usually vanadium oxide, V₂O₅) at high temperature to form sulfur trioxide (SO₃). This reaction is important in the industrial production of sulfuric acid. The balanced equation is:
$2SO_2 + O_2 \rightarrow 2SO_3$.
356. What is the product when calcium oxide (CaO) reacts with sulfur trioxide (SO₃)?
ⓐ. Calcium hydroxide (Ca(OH)₂)
ⓑ. Calcium carbonate (CaCO₃)
ⓒ. Calcium phosphate (Ca₃(PO₄)₂)
ⓓ. Calcium sulfate (CaSO₄)
Correct Answer: Calcium sulfate (CaSO₄)
Explanation: When calcium oxide (CaO) reacts with sulfur trioxide (SO₃), it forms calcium sulfate (CaSO₄). This reaction is commonly used in the industrial production of sulfuric acid and in the manufacturing of plaster:
$CaO + SO_3 \rightarrow CaSO_4$.
357. What is the product when sodium hydroxide (NaOH) reacts with chlorine (Cl₂)?
ⓐ. Sodium chloride (NaCl) and sodium hypochlorite (NaOCl)
ⓑ. Sodium chloride (NaCl) and oxygen (O₂)
ⓒ. Sodium chloride (NaCl) and sodium chlorate (NaClO₃)
ⓓ. Sodium hydroxide (NaOH) and hydrogen chloride (HCl)
Correct Answer: Sodium chloride (NaCl) and sodium hypochlorite (NaOCl)
Explanation: When sodium hydroxide (NaOH) reacts with chlorine (Cl₂) in cold conditions, it produces sodium chloride (NaCl) and sodium hypochlorite (NaOCl). This reaction is important in the preparation of bleach:
$Cl_2 + 2NaOH \rightarrow NaCl + NaOCl + H_2O$.
358. What happens when potassium (K) reacts with water?
ⓐ. Potassium hydroxide (KOH) and oxygen gas (O₂) are formed
ⓑ. Potassium chloride (KCl) and water (H₂O) are formed
ⓒ. Potassium hydroxide (KOH) and hydrogen gas (H₂) are formed
ⓓ. Potassium oxide (K₂O) and hydrogen gas (H₂) are formed
Correct Answer: Potassium hydroxide (KOH) and hydrogen gas (H₂) are formed
Explanation: When potassium (K) reacts with water, potassium hydroxide (KOH) and hydrogen gas (H₂) are formed. This is an exothermic reaction that produces heat and hydrogen gas. The reaction is:
$2K + 2H_2O \rightarrow 2KOH + H_2$.
359. What is the balanced chemical equation for the reaction between calcium hydroxide (Ca(OH)₂) and hydrochloric acid (HCl)?
ⓐ. $Ca(OH)_2 + 2HCl \rightarrow CaCl_2 + 2H_2O$
ⓑ. $Ca(OH)_2 + HCl \rightarrow CaCl_2 + H_2O$
ⓒ. $Ca(OH)_2 + 2HCl \rightarrow CaCl_2 + H_2O + CO_2$
ⓓ. $Ca(OH)_2 + HCl \rightarrow CaCl_2 + H_2O + CO_2$
Correct Answer: $Ca(OH)_2 + 2HCl \rightarrow CaCl_2 + 2H_2O$
Explanation: This is an acid-base neutralization; to balance the two chloride ions ($Cl^-$) needed for $CaCl_2$, two $HCl$ are required, which also produces two $H_2O$, making the balanced equation $Ca(OH)_2 + 2HCl \rightarrow CaCl_2 + 2H_2O$.
Welcome to Class 11 Chemistry MCQs – Chapter 10: The s-Block Elements (Part 4). This section completes the chapter with a focus on advanced applications of s-block elements, including their role in medicine and industry.
Topics covered in Part 4 (59 MCQs)
- Applications of s-block elements in medicine (e.g., magnesium sulfate) and industry (e.g., sodium hydroxide in soap-making)
- Properties of compounds of alkali and alkaline earth metals and their real-world uses
- 👉 Total MCQs in this chapter: 359 (100 + 100 + 100 + 59)
- 👉 This page: Final set of 59 solved MCQs
- 👉 Explore more: Continue exploring other chapters and subjects