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 1951: The constituent of air necessary in the rusting process are Options:
  A) O₂ and H₂O
  B) Ar and CO₂
  C) CO₂ and H₂O
  D) O₂ and CO₂
  Show Answer
  The correct answer is D .
• Question 1952:

  Isotopes of an element have

  Options:
  A) The same number of protons but different numbers of neutrons.
  B) The same number of neutrons and electrons
  C) The same number of protons and neutrons
  D) The same number of protons and electrons
  Show Answer
  The correct answer is A .
• Question 1953: The approximate volume of air containing 10cm³ of oxygen is? Options:
  A) 20 cm³
  B) 25 cm³
  C) 50 cm³
  D) 100 cm³
  Show Answer
  The correct answer is C .
• Question 1954: 20 cm³ of 1 M H₂SO₄ is mixed 20 cm³ of 1 M NaOH. The resulting solution is? Options:
  A) acidic with a molarity of 0.50 M H₂SO₄
  B) acidic with a molarity of 0.25 H₂SO₄
  C) neutral
  D) alkaline with a molarity of 0.25 M NaOH
  E) alkaline with a molarity of 0.50 M NaOH
  Show Answer
  The correct answer is A .
• Question 1955:

  A mixture of iron and sulphur can be separated by dissolving the mixture in?

  Options:
  A) steam
  B) dilute hydrochloric acid
  C) dilute sodium hydroxide
  D) benzene
  Show Answer
  The correct answer is B .
• Question 1956:

  Al₂O_3(s) + 3H₂SO_4(aq) → Al₂(SO_4(aq)) + 3H_2(I)O

  Al₂O_3(s) + 2NaOH_(aq)) + 3H_2(I)O → 2NaAl(OH)_4(aq)).

  We can conclude from the equations above that Al₂O_3(s) is?

  Options:
  A) an acidic oxide
  B) an amphoteric oxide
  C) a basic oxide
  D) a neutral oxide
  Show Answer
  The correct answer is B .
• Question 1957: Addition of dilute hydrochloride acid to an aqueous solution of a crystalline salt yield a yellow precipitate and a gas which turned dichromate paper green. The crystalline salt was probably? Options:
  A) Na₂SO₄
  B) Na₂S
  C) Na₂S₂O₃.5H₂O
  D) Na₂CO₃
  E) NaHCO₃
  Show Answer
  The correct answer is C .
• Question 1958:

  A solution X, on mixing with AgNO${}_3$ solution gives a white precipitate soluble in aqueous NH${}_3$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

  Options:
  A) Al${}^{3+}$, Cl${}^{-}$
  B) Hg${}^{+}$, SO${}_4^{2-}$
  C) Pb${}^{2+}$, Cl${}^{-}$
  D) Ag${}^{+}$, SO${}_4^{2-}$
  Show Answer
  The correct answer is C .
• Question 1959: The role of sodium chloride in the preparation of soap is to? Options:
  A) purify the soap
  B) separate the soap from glycerol
  C) accelerate the decomposition of the fat or oil
  D) react with glycerol
  Show Answer
  The correct answer is B .
• Question 1960: An oxide XO₂ has a vapour density of 32. What is the atomic mass of X? Options:
  A) 20
  B) 32
  C) 14
  D) 12
  Show Answer
  The correct answer is B .