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 1981: In the preparation of oxygen by heating KClO₃ in the presence of MnO₂, only moderate heat is needed because the catalyst acts by Options:
  A) lowering the pressure of the reaction
  B) increasing the surface area of the reactant
  C) increase the rate of the reaction
  D) lowering the energy barrier of the reaction
  Show Answer
  The correct answer is D .
• Question 1982: The mathematical expression of PH is Options:
  A) log ₁₀[OH^-]
  B) log ₁₀1/[H ₃ O⁺]
  C) log ₁₀[H ₃ O⁺]
  D) log ₁₀1/[OH ^-]
  Show Answer
  The correct answer is B .
• Question 1983: A particle that contains a protons, 10 neutrons and 10 electrons is Options:
  A) positive ion
  B) neutral atom of a metal
  C) neutral atom of a non-metal
  D) negative ion
  Show Answer
  The correct answer is D .
• Question 1984: A fixed mass of gas a volume of 92cm³ at 3°C. When will be its volume at 18C if the pressure remains constant? Options:
  A) 15.3cm³
  B) 87.3cm³
  C) 2.0cm³
  D) 97.0cm³
  Show Answer
  The correct answer is D .
• Question 1985: What is the concentration of H⁺ ions in moles per dm³ of a sodium of pH 4.398? Options:
  A) 4.0 χ 10^-5
  B) 0.4 χ 10^-5
  C) 4.0 χ 10^-3
  D) 0.4 χ 10^-3
  Show Answer
  The correct answer is A .
• Question 1986: The gas that gives brown colouration in brown ring test is Options:
  A) NO
  B) CO₂
  C) NO₂
  D) CO
  Show Answer
  The correct answer is A .
• Question 1987:

  

  The acidic hydrogen in the compound is the hydrogen attached to carbon number

  Options:
  A) 5
  B) 4
  C) 3
  D) 1
  Show Answer
  The correct answer is D .
• Question 1988: The standard enthalpies of formation of CO_2(g), H₂O(g) and CO_(g) in kJ mol^- are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO_(g) + H_2(g)O → CO_2(g) + H_2(g)? Options:
  A) -42 KJ mol^-
  B) +42 KJ mol^-
  C) -262 KJ mol^-
  D) +262 KJ mol^-
  Show Answer
  The correct answer is A .
• Question 1989:

  The general formula of alkanoates is?

  Options:
  A) $RCHO$
  B) $R_{2}CO$
  C) $RCOOH$
  D) $RCOO{R}^{\prime }$
  Show Answer
  The correct answer is D .
• Question 1990: 2SO_2(g) + O_2(g) ↔ 2SO_3(g). In the chemical reaction above, the substance that will increase the rate of production of sulphur (VI) oxide is Options:
  A) manganese (IV) oxide
  B) finely divided iron
  C) vanadium (V) oxide
  D) nickel
  Show Answer
  The correct answer is C .