Critical Thinking Questions: Electrolytes, Non-Electrolytes and Electrolysis

Type I

Q1: During the electrolysis of molten lead(II) bromide, a metal is deposited at the cathode. Which property of the metal is immediately observed following its deposition?
(a) The metal is in a liquid state at room temperature.
(b) The metal is a good conductor of electricity.
(c) The metal starts to float on the surface of the molten salt.
(d) The metal has a distinct purple colour.

Q2: A solution of sodium sulphate is electrolysed using inert electrodes. The solution is observed to conduct electricity and undergo chemical changes at the electrodes. Which of the following best describes sodium sulphate in this scenario?
(a) Non-electrolyte
(b) Weak electrolyte
(c) Strong electrolyte
(d) Insulator

Q3: An aqueous solution of compound M is electrolysed using inert electrodes. The pH of the solution decreases over time. Which of the following is likely to be compound M?
(a) Sodium sulphate
(b) Potassium nitrate
(c) Hydrochloric acid
(d) Ammonium hydroxide

Q4: During the electrolysis of molten lead bromide, a metal is deposited at the cathode. What observation is expected at the anode?
(a) Deposition of lead
(b) Release of oxygen gas
(c) Release of bromine gas
(d) No observable change

Q5: When molten lead bromide is electrolysed, which of the following gases is released at the anode?
(a) Hydrogen
(b) Oxygen
(c) Bromine
(d) Chlorine

Q6: A piece of copper is placed into a solution of silver nitrate. After some time, a solid deposit is observed on the copper. What is the composition of the deposit?
(a) Copper nitrate
(b) Silver
(c) Copper oxide
(d) Silver oxide

Q7: In the electrolysis of acidified water using platinum electrodes, what is the ratio of the volume of hydrogen gas to oxygen gas collected?
(a) 4:1
(b) 2:1
(c) 1:1
(d) 1:2

Q8: When a saturated solution of copper (II) sulphate is electrolysed using copper electrodes, what change in colour of the solution is observed?
(a) The solution turns from blue to colourless.
(b) The solution turns from colourless to blue.
(c) The solution remains blue throughout the process.
(d) The solution turns green.

Q9: When magnesium is obtained through electrolysis using fused magnesium chloride, what occurs at the anode?
(a) Magnesium ions gain electrons to form magnesium metal.
(b) Chloride ions lose electrons to form chlorine gas.
(c) Oxygen is produced as a by-product of the electrolysis.
(d) The anode material reacts with magnesium to form a compound.

Q10: If a piece of iron is electroplated with nickel using a nickel sulphate solution, what would be the expected change at the cathode over time?
(a) The cathode will gain a coating of nickel.
(b) The cathode will gradually dissolve into the solution.
(c) The cathode will increase in size due to deposition of SO₄²⁻.
(d) The cathode will remain unchanged as the nickel is deposited on the anode.

Type II

Q11: During the light-dependent reactions of photosynthesis, what is the immediate fate of the photons absorbed by chlorophyll?
A. They are used to split water molecules into hydrogen and oxygen.
B. They are transformed directly into chemical energy in the form of ATP.
C. They are used in the Calvin cycle to produce glucose.
D. They generate heat to increase the temperature of the chloroplast.
(a) only A
(b) only B
(c) A and B
(d) B and C

Q12: Which of the following is not a product of the light-dependent reactions of photosynthesis?
A. Oxygen
B. ATP
C. NADPH
D. Glucose
(a) only A
(b) only D
(c) B and C
(d) A and C

Q13: What is the primary role of stomata in the leaves of plants during photosynthesis?
A. Absorption of light energy
B. Release of oxygen and uptake of carbon dioxide
C. Synthesis of glucose from carbon dioxide
D. Conversion of light energy into chemical energy
(a) only A
(b) only B
(c) B and D
(d) C and D

Q14: What happens to the chlorophyll in plants when they are exposed to too much light?
A. It becomes more efficient in capturing light energy.
B. It undergoes a structural change to protect the plant cells.
C. It is destroyed, affecting the plant's ability to photosynthesise.
D. It starts to produce oxygen at a higher rate.
(a) only A
(b) only C
(c) B and D
(d) A and D

Q15: In the light-dependent reactions of photosynthesis, what is the immediate fate of the electrons energised by sunlight?
A. They are transferred to carbon dioxide (CO₂) directly.
B. They move to the electron transport chain and then to NADP⁺ to form NADPH.
C. They are used to split water molecules to release oxygen.
D. They convert ADP and inorganic phosphate into ATP.
(a) only A
(b) only B
(c) B and C
(d) B and D

Q16: During photosynthesis, the oxygen released into the atmosphere is a result of which process?
A. Carbon fixation in the Calvin cycle.
B. The breakdown of glucose during respiration.
C. The photolysis of water in the light-dependent reactions.
D. The reduction of NADP⁺ to NADPH.
(a) only A
(b) only C
(c) A and B
(d) C and D

Q17: What is the likely consequence of continuously increasing CO₂ concentration in the air on the rate of photosynthesis in plants?
A. The rate of photosynthesis will increase indefinitely with CO₂ concentration.
B. The rate of photosynthesis will initially increase but then stabilize at a certain point.
C. The rate of photosynthesis will decrease due to CO₂ toxicity.
D. The rate of photosynthesis will not be affected by changes in CO₂ concentration.
(a) only A
(b) only B
(c) A and C
(d) B and C

Q18: In the experiment that demonstrates the necessity of carbon dioxide for photosynthesis, what does the potassium hydroxide (KOH) do?
A. It releases carbon dioxide into the flask for the leaf to use.
B. It absorbs carbon dioxide, creating a CO₂-deficient environment.
C. It changes colour to indicate the presence of oxygen.
D. It acts as a source of light for photosynthesis.
(a) only A
(b) only B
(c) B and C
(d) only D

Q19: If a leaf is partially covered with black paper and exposed to light, what outcome is expected after testing with iodine solution?
A. The entire leaf turns blue-black indicating starch presence.
B. Only the parts exposed to light turn blue-black indicating starch presence.
C. Only the parts covered by black paper turn blue-black.
D. The leaf remains unchanged because the paper inhibits photosynthesis.
(a) only A
(b) only B
(c) only C
(d) A and C

Q20: According to the information on the carbon cycle, which of the following processes do not release carbon dioxide into the atmosphere?
A. The combustion of fossil fuels.
B. The decomposition of dead plants and animals by bacteria and fungi.
C. The respiration by plants and animals.
D. The process of photosynthesis in green plants.
(a) only A
(b) only B
(c) only D
(d) A and B