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NECO SSCE Chemistry 2003 past questions and answers

This 2003 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 2003 set with instant marking.

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Sample NECO SSCE Chemistry 2003 questions

1. An atom has 17 protons and a mass number of 35; how many neutrons does it contain?
  1. 17
  2. 35
  3. 18
  4. 52

Answer: C. 18

The number of neutrons is the mass number minus the proton number, so 35 - 17 = 18.

2. An element has the shell electron arrangement 2,8,7; which group contains it in the modern periodic table?
  1. Group 17
  2. Group 1
  3. Group 2
  4. Group 18

Answer: A. Group 17

Seven outer-shell electrons place the element among the halogens in Group 17.

3. Which description best explains the bond between hydrogen and chlorine in a hydrogen chloride molecule?
  1. Transfer of two electrons from hydrogen to chlorine
  2. Attraction between oppositely charged ions
  3. Sharing of a pair of electrons by two chlorine atoms
  4. Sharing of one pair of electrons between hydrogen and chlorine

Answer: D. Sharing of one pair of electrons between hydrogen and chlorine

Hydrogen and chlorine form a covalent bond by sharing one pair of electrons.

4. What generally happens to atomic radius as one moves from left to right across a period?
  1. It increases because more shells are added
  2. It decreases because effective nuclear attraction increases
  3. It remains constant because the shell number is unchanged
  4. It first doubles and then becomes zero

Answer: B. It decreases because effective nuclear attraction increases

Across a period, nuclear charge rises while electrons enter the same main shell, pulling them closer to the nucleus.

5. How many molecules are present in 0.50 mol of carbon dioxide? Use Avogadro constant = 6.02 x 10^23 mol^-1.
  1. 1.20 x 10^24
  2. 6.02 x 10^22
  3. 3.01 x 10^23
  4. 6.02 x 10^23

Answer: C. 3.01 x 10^23

The number of molecules is 0.50 x 6.02 x 10^23 = 3.01 x 10^23.

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