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 201: If an equilibrium reaction has ∆H < O, the reaction will proceed favorably in the forward reaction at? Options:
  A) low temperatures
  B) high temperatures
  C) all temperatures
  D) all pressures
  Show Answer
  The correct answer is A .
• Question 202: Which of the following compounds is NOT an isomers of 2,2 dimethylbutane? Options:
  A) 2-methylbutane
  B) 3-methylpentane
  C) 2,3-dimethylbutane
  D) 2-methylpentane
  Show Answer
  The correct answer is A .
• Question 203: The effect of the presence of impurities such as carbon and sulphur on iron is that they Options:
  A) give it high tensile strenght
  B) make it malleable and ductile
  C) increase its melting point
  D) lower its melting point
  Show Answer
  The correct answer is D .
• Question 204: Which of these represents a redox reaction? Options:
  A) AgNO₃ + NaCl → AgCAl + NaNO₃
  B) H₂S + Pb(NO₃) → PbS + 2HNO₃
  C) CaCO₃ → CaO + CO₂
  D) Zn + 2HCl → ZnCl₂ + H₂
  Show Answer
  The correct answer is D .
• Question 205: Which of the following is used as an 'anti-knock' in automobile engines? Options:
  A) Tetramethyl silane
  B) Lead tetra-ethyl
  C) Glycerol
  D) n-heptane
  Show Answer
  The correct answer is B .
• Question 206: Which of the following pairs has compounds that are isomers? Options:
  A) Propanal and propanone
  B) Ethanoic acid and ethylmethanoate
  C) Ethanoic acid and ethane-1, 2-diol
  D) 2-methylbutane and 2, 2-dimethylbutane
  Show Answer
  The correct answer is D .
• Question 207: Water can be identified by the use of? Options:
  A) anhydrous copper (II) tetraoxosulphate (VI)
  B) anhydrous sodium trioxocarbonate (IV)
  C) potassium heptaoxochromate (VII)
  D) copper (II) trioxocaronate (IV)
  Show Answer
  The correct answer is A .
• Question 208: Crude copper can be purified by the electrolysis of CuSO_4(aq) if? Options:
  A) platinum electrodes are used
  B) the crude copper is made the anode of the cell
  C) the crude copper is made the cathode of the cell
  D) crude copper electrodes are used
  Show Answer
  The correct answer is B .
• Question 209:

  The nucleusof a hydrogen atom consist of a?

  Options:
  A) 1 proton only
  B) 1 proton, 2 neutron
  C) 1 neutron only
  D) 1 electron only
  Show Answer
  The correct answer is A .
• Question 210:

  A compound contains 31.91% potassium, 28.93% chlorine and the rest oxygen. What is the chemical formula of the compound?

  [K = 39, Cl = 35.5, O = 16]

  Options:
  A) KClO₄
  B) KClO
  C) KClO₂
  D) KClO₃
  Show Answer
  The correct answer is D .