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NECO SSCE Chemistry 2021 past questions and answers

This 2021 NECO SSCE Chemistry set has 40 practice questions. Try these 5 free sample questions, tap a question to reveal the answer and explanation. Then practise the whole 2021 set with instant marking.

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Sample NECO SSCE Chemistry 2021 questions

1. During the electrolysis of aqueous copper(II) sulfate using inert electrodes, which substance is deposited at the cathode?
  1. Oxygen
  2. Copper
  3. Sulfur
  4. Hydrogen sulfate

Answer: B. Copper

Copper(II) ions are preferentially reduced at the cathode to form copper metal.

2. What is the oxidation number of manganese in KMnO4?
  1. +2
  2. +4
  3. +7
  4. -1

Answer: C. +7

Potassium is +1 and four oxygen atoms total -8, so manganese must be +7 for the compound to be neutral.

3. For a reaction that is first order with respect to reactant X, what happens to its rate when the concentration of X is doubled while other conditions remain constant?
  1. It doubles
  2. It is halved
  3. It becomes four times as large
  4. It remains unchanged

Answer: A. It doubles

For a first-order reaction, rate is directly proportional to the concentration of X.

4. For the equilibrium N2(g) + 3H2(g) <=> 2NH3(g), what is the effect of increasing pressure at constant temperature?
  1. The equilibrium shifts left
  2. The equilibrium is unaffected
  3. The amount of hydrogen increases
  4. The equilibrium shifts right

Answer: D. The equilibrium shifts right

Higher pressure favors the side with fewer gas molecules, which is the ammonia side.

5. Which indicator is most suitable for titrating aqueous ammonia with hydrochloric acid?
  1. Litmus only
  2. Methyl orange
  3. Universal indicator paper only
  4. Starch solution

Answer: B. Methyl orange

Methyl orange gives a clear endpoint for a strong acid-weak base titration.

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