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NECO SSCE Chemistry 2020 past questions and answers

This 2020 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 2020 set with instant marking.

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Sample NECO SSCE Chemistry 2020 questions

1. At 30 degrees C, 45 g of a salt dissolve in 100 g of water to form a saturated solution. How much more of the salt must be added to 100 g of water already containing 38 g to make it saturated at that temperature?
  1. 7 g
  2. 38 g
  3. 45 g
  4. 83 g

Answer: A. 7 g

The solution can hold 45 g, so the additional amount needed is 45 g - 38 g = 7 g.

2. What volume of 0.10 mol dm-3 sodium hydroxide is required to neutralize 25.0 cm3 of 0.20 mol dm-3 hydrochloric acid?
  1. 12.5 cm3
  2. 50.0 cm3
  3. 25.0 cm3
  4. 75.0 cm3

Answer: B. 50.0 cm3

The reaction is 1:1, so 0.005 mol of acid requires 0.005 mol of base, which occupies 0.050 dm3.

3. What is the oxidation number of sulfur in H2SO4?
  1. +4
  2. -2
  3. +6
  4. +2

Answer: C. +6

The oxidation numbers sum to zero, giving 2(+1) + S + 4(-2) = 0 and S = +6.

4. Which substance is produced at the cathode during the electrolysis of molten sodium chloride?
  1. Chlorine
  2. Hydrogen
  3. Sodium hydroxide
  4. Sodium

Answer: D. Sodium

Sodium ions gain electrons at the cathode to form sodium atoms.

5. A reaction releases 85 kJ of heat when 1 mol of reactant reacts. How much heat is released when 2 mol react completely under the same conditions?
  1. 170 kJ
  2. 42.5 kJ
  3. 85 kJ
  4. 340 kJ

Answer: A. 170 kJ

The heat released is proportional to the amount reacting, so 2 x 85 kJ = 170 kJ.

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