Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 1651: What is the oxidation number of Z in K₃ZCl₆? Options:
  A) -3
  B) +3
  C) -6
  D) +6
  Show Answer
  The correct answer is B .
• Question 1652:

  2CO_(g) + O_2(g) → 2CO_2(g)

  Given that ΔH[CO]is -110.4 kJmol^-1 and ΔH[CO₂] is -393.0 kJmol^-1, the energy change for the reaction above is

  Options:
  A) -503.7 kJ
  B) -282.6 kJ
  C) +282.6 kJ
  D) +503.7 kJ
  Show Answer
  The correct answer is B .
• Question 1653: When a little brine was added to a metal nitrate a white precipitate was formed which first turned violet and then black on exposure to ai. The metal nitrate is therefore? Options:
  A) sodium nitrate
  B) mercuric nitrate
  C) lithium nitrate
  D) silver nitrate
  E) potassium nitrate
  Show Answer
  The correct answer is D .
• Question 1654: 2X_(g) + Y_(g) → Z_(g): In the equation above, The rate of formation of Z is found to be independent of the concentration of Y and to quadruple when the concentration of X is doubled. The correct equation for the reaction is? Options:
  A) R = k (X)(Y)
  B) R = K (X) ° (Y)
  C) R = K (X) ° (Y) ₂
  D) R = K (X) ₂(Y)°
  Show Answer
  The correct answer is D .
• Question 1655: What current in ampere will deposit 0.27g of aluminium in 2 hours? [Al = 27, F = 96500C]. Options:
  A) 3.2
  B) 8
  C) 0.4
  D) 16
  Show Answer
  The correct answer is C .
• Question 1656: Sodium and potassium belong to the same group of the Periodic Table. This is because? Options:
  A) both are metals
  B) both are soft and lighter than water
  C) both form cations by losing electrons
  D) both have identical electronic configuration
  E) both react with water vigorously
  Show Answer
  The correct answer is D .
• Question 1657:

  

  Use the following option above to answer this question. Which of the following is the functional group of carboxylic acids?

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is D .
• Question 1658: The general formula of an alkyl halide (where X represents the halide) is? Options:
  A) C_nH_2n2X
  B) C_nH_2n + ₁X
  C) C_nH_2n + ₂X
  D) C_nH_2nX
  Show Answer
  The correct answer is B .
• Question 1659: Group VII elements are Options:
  A) monoatmic
  B) good oxidizing agents
  C) highly electropositive
  D) electron donors
  Show Answer
  The correct answer is B .
• Question 1660:

  2Na_(s) + 2H₂O_(l) → 2NaOH_(aq) + H_2(g)

  From the equation above, calculate the mass of sodium hydroxide produced by 2.3g of sodium.

  [H = 1, O = 16, Na = 23]

  Options:
  A) 0.40g
  B) 0.80g
  C) 4.00g
  D) 8.00g
  Show Answer
  The correct answer is C .