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 91: The pair of metals in the reactivity series that are usually extracted by the electrolysis of their ores is Options:
  A) magnesium and zinc
  B) magnesium and calcium
  C) copper and zinc
  D) lead and calcium
  Show Answer
  The correct answer is B .
• Question 92:

  

  The compound above is an

  Options:
  A) ether
  B) ester
  C) alkanal
  D) alkanol
  Show Answer
  The correct answer is B .
• Question 93: When chlorine is passed into water and subsequently exposed to sunlight, the gas evolved is? Options:
  A) HCl
  B) HOCl
  C) O₂
  D) Cl₂O
  Show Answer
  The correct answer is C .
• Question 94: An emulsion may be produced by shaking a detergent solution with Options:
  A) palm wine
  B) ethanoic acid
  C) palm oil
  D) water
  Show Answer
  The correct answer is C .
• Question 95: The number of atoms in one mole of a substance is equal to? Options:
  A) the atomic number
  B) the avogadro number
  C) the gas constant
  D) the number of neutrons
  E) the number of electrons
  Show Answer
  The correct answer is B .
• Question 96:

  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 97: Chlorine consisting of two isotopes of mass number 35 and 37 in the ratio 3:1 has an atomic mass of 35.5. Calculate the relative abundance of the isotopes of mass number 37 Options:
  A) 20
  B) 25
  C) 60
  D) 75
  Show Answer
  The correct answer is B .
• Question 98:

  On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell

  Options:
  A) cu${}^{2+}$
  B) sn${}^{2+}$
  C) fe${}^{2+}$
  D) zn${}^{2+}$
  Show Answer
  The correct answer is A .
• Question 99:

  Which trace gas in the atmosphere plays a significant role in the greenhouse effect?

  Options:
  A) Oxygen
  B) Argon
  C) Carbon dioxide
  D) Nitrogen
  Show Answer
  The correct answer is C .
• Question 100: Which volume of 0.5 M H ₂SO₄ will exactly neutralize 20 cm ³ of 0.1 M NaOH solution? Options:
  A) 2.0 cm ³
  B) 5.0 cm ³
  C) 6.8 cm ³
  D) 8.3 cm ³
  E) 10.4 cm ³
  Show Answer
  The correct answer is A .