GCSE Chemistry 4 — Questions and Answers
Question 1: Which factor does NOT increase the rate of a chemical reaction?
- Increasing temperature
- Adding a catalyst
- Decreasing concentration of reactants (Correct answer)
- Increasing surface area of a solid
Correct answer: Decreasing concentration of reactants
Decreasing the concentration of reactants reduces the frequency of collisions, thereby slowing the reaction rate.
Question 2: What is the name of the process by which plants convert carbon dioxide and water into glucose using sunlight?
- Respiration
- Combustion
- Photosynthesis (Correct answer)
- Fermentation
Correct answer: Photosynthesis
Photosynthesis is the process in which plants use light energy to convert CO2 and water into glucose and oxygen.
Question 3: In a reversible reaction at equilibrium, what does Le Chatelier's principle predict if pressure is increased?
- The reaction always shifts to produce more products
- The reaction shifts to the side with fewer moles of gas (Correct answer)
- The reaction shifts to the side with more moles of gas
- Equilibrium is not affected by pressure changes
Correct answer: The reaction shifts to the side with fewer moles of gas
Le Chatelier's principle states that increasing pressure shifts equilibrium toward the side with fewer moles of gas to reduce pressure.
Question 4: Which of the following is the correct electron configuration for a sodium atom (atomic number 11)?
- 2, 8, 2
- 2, 8, 1 (Correct answer)
- 2, 9
- 3, 8
Correct answer: 2, 8, 1
Sodium has 11 electrons arranged as 2 in the first shell, 8 in the second, and 1 in the third shell.
Question 5: What product forms at the anode during the electrolysis of copper sulfate solution using copper electrodes?
- Oxygen gas is released
- Copper is deposited
- The copper anode dissolves into solution (Correct answer)
- Sulfate ions are discharged
Correct answer: The copper anode dissolves into solution
With copper electrodes, the copper anode dissolves (oxidises) as copper atoms lose electrons and enter the solution.
Question 6: Which of the following molecules has a linear shape?
- Water (H2O)
- Ammonia (NH3)
- Carbon dioxide (CO2) (Correct answer)
- Methane (CH4)
Correct answer: Carbon dioxide (CO2)
CO2 has two double bonds and no lone pairs on the central carbon, resulting in a linear geometry with a 180° bond angle.
Question 7: What is the empirical formula of a compound that is 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?
- C2H4O2
- CH2O (Correct answer)
- C3H6O3
- C2H2O
Correct answer: CH2O
Dividing each percentage by the atomic mass (C: 40/12 ≈ 3.33, H: 6.7/1 ≈ 6.7, O: 53.3/16 ≈ 3.33) gives a 1:2:1 ratio, so the empirical formula is CH2O.
GCSE Chemistry 4
Which factor does NOT increase the rate of a chemical reaction?