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 81:

  When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

  Options:
  A) Oxyethene
  B) Oxyhydrocarbon flame
  C) Oxyacetylene flame
  D) Oxymethane flame
  Show Answer
  The correct answer is C .
• Question 82:

  A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].

  Options:
  A) 2.7g
  B) 1.2g
  C) 0.9g
  D) 0.3g
  Show Answer
  The correct answer is A .
• Question 83: Certain useful waxes are composed mainly of Options:
  A) amino acids
  B) glycerols
  C) alkanols
  D) alkanoates
  Show Answer
  The correct answer is B .
• Question 84:

  If the cost of electricity required to discharge 10g of an ion X${}^{3+}$ is N20.00, how much would it cost to discharge 6g of ion Y${}^{2+}$?

  [1 faraday = 96,500C, atomic masses are X = 27, Y = 24]

  Options:
  A) N10.00
  B) N6.00
  C) N20.00
  D) N9.00
  Show Answer
  The correct answer is D .
• Question 85: In what way is equilibrium constant for the forward reaction related to that of the reversed reaction? Options:
  A) The additional of the two is expected to be one
  B) The product of the two is expected to be one
  C) The two equilibrium constants are identical
  D) The product of the two is always greater than one
  Show Answer
  The correct answer is A .
• Question 86:

  At 2.0 atm pressure, the volume of a gas is 4.0 L. If the pressure is reduced to 1.0 atm while keeping the temperature constant, what will be the new volume of the gas?

  Options:
  A) 2.0 L
  B) 6.0 L
  C) 8.0 L
  D) 4.0 L
  Show Answer
  The correct answer is C .
• Question 87: Neutral atoms of neon with atomic number 10 have the same number of electron as Options:
  A) O²⁺
  B) Ca²⁺
  C) K⁺
  D) Mg²⁺
  Show Answer
  The correct answer is D .
• Question 88: The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is Options:
  A) Na₂SO₄
  B) Na₂SO₃
  C) Na₂S
  D) Na₂CO₃
  Show Answer
  The correct answer is B .
• Question 89: In which of the following are water molecules in the most disorderly arrangement? Options:
  A) Ice at -10°C
  B) Ice at 0°C
  C) Water at 100°C
  D) Steam at 100°C
  Show Answer
  The correct answer is D .
• Question 90: In the laboratory preparation of ethyl ethanoate, the water present in the mixture is removed using a solution of Options:
  A) an hydrous CaCl₄
  B) concentrated NaCO₄
  C) dilute NaOH
  D) concentrated H₄SO₄
  Show Answer
  The correct answer is D .