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 1741:

  H₃PO_4(aq) + H₂O_(l) ↔ H₂PO₄^-_(aq) + H₃O⁺_(aq)

  ΔH = -13kJ at 298K

  In the reaction above, an increase in temperature would

  Options:
  A) slow downthe reverse reaction
  B) have no effect on the reaction
  C) favour the reverse reaction
  D) favour the forward reaction
  Show Answer
  The correct answer is C .
• Question 1742:

  X is a substance which liberates CO${}_2$ on treatment with concentrated H${}_2$SO${}_4$. A warm solution of X can decolorize acidified KMnO${}_4$. X is

  Options:
  A) HCOOH
  B) NaHCO${}_3$
  C) FeCO${}_3$
  D) H${}_2$C${}_2$O${}_4$
  Show Answer
  The correct answer is D .
• Question 1743: Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by Options:
  A) dissolving it in water, recrystallizing it and then drying in the oven
  B) passing it through a concentrated aqueous solution of sodium hydroxide
  C) passing it through calcium oxide
  D) passing it through concentrated sulphuric acid
  E) passing it through anhydrous calcium choride
  Show Answer
  The correct answer is C .
• Question 1744:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  Reaction of X with yeast forms the basis of the

  Options:
  A) plastic industry
  B) textile industry
  C) brewing industry
  D) soap industry
  E) dyeing industry
  Show Answer
  The correct answer is C .
• Question 1745:

  Identify the reducing agent in the following reaction:
  Zn + CuSO${}_4$ ZnSO${}_4$ + Cu

  Options:
  A) Cu
  B) Zn
  C) ZnSO${}_4$
  D) CuSO${}_4$
  Show Answer
  The correct answer is B .
• Question 1746: Calculate the number of moles of HCl present in 20cm³ of a 0.75M solution of the acid Options:
  A) 0.015 mole
  B) 0.038 mole
  C) 3.800 moles
  D) 1.500 moles
  Show Answer
  The correct answer is A .
• Question 1747: A burning candle produces water and Options:
  A) Carbon (II) oxide
  B) Carbon (IV) oxide
  C) Oxygen
  D) Hydrogen
  Show Answer
  The correct answer is B .
• Question 1748: The structural component that makes detergent dissolve more quickly in water than soap is Options:
  A) -SO₃- Na⁺
  B) -COO-Na^-
  C) -SO₄- Na⁺
  D) -COO-K⁺
  Show Answer
  The correct answer is A .
• Question 1749: The general formula of an alkyl halide (where X represents the halide) is? Options:
  A) C_nH_2n2X
  B) C_nH_2n + ₁X
  C) C_nH_2n + ₂X
  D) C_nH_2nX
  Show Answer
  The correct answer is B .
• Question 1750: A fixed mass of gas has a volume of 92cm₃ at 3 ^oC. When will be its volume at 18 ^oC if the pressure remains constant Options:
  A) 15.3cm³
  B) 87.3cm³
  C) 552.0cm³
  D) 97.0cm³
  Show Answer
  The correct answer is D .