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 1051:

  What is the product of the electrolysis of aqueous sodium chloride (NaCl) using inert electrodes?

  Options:
  A) Hydrogen gas at the cathode and chlorine gas at the anode
  B) Hydrogen gas at the cathode and oxygen gas at the anode
  C) Sodium metal at the cathode and chlorine gas at the anode
  D) Sodium metal at the cathode and oxygen gas at the anode
  Show Answer
  The correct answer is A .
• Question 1052:

  NH₄Cl_(s) ↔ NH_3(g) + HCL_(g)

  The reaction above can only attain equilibrium if

  Options:
  A) a gaseous reactant is added
  B) one of the products is removed
  C) it is in a closed system
  D) it is an open system
  Show Answer
  The correct answer is C .
• Question 1053: In the manufacture of iron in the blast furnace, iron (lll) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions? Options:
  A) the coke is a powerful reducing agent and easily converts the iron oxide to iron
  B) the calcuim carbonate reacts with SiO₂ an earthly impurity in the ore, to from calcuim silicate
  C) the coke will react with the iron produced to form steel
  D) all the carbondioxide required in the process comes from the decomposition of the calcium carbonate
  E) the calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity
  Show Answer
  The correct answer is E .
• Question 1054: Which of the following gases can be collected by the upward displacement of air? Options:
  A) NO
  B) H ₂
  C) NH₃
  D) Cl ₂
  Show Answer
  The correct answer is D .
• Question 1055:

  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 1056: Calculate the quantity of electricity in coulombs required to liberate 10g of copper from a copper compound[Cu=64, F = 96500 Cmol^-1] Options:
  A) 32395.5
  B) 30156.3
  C) 60784.5
  D) 15196.5
  Show Answer
  The correct answer is B .
• Question 1057: N₂O_4(g)→ 2NO_2(g)In the endothermic reaction above, more products formed will be favored by Options:
  A) A constant values
  B) an increase in pressure
  C) a decrease pressure
  D) a decrease volume
  Show Answer
  The correct answer is C .
• Question 1058: Which of the following is a example of a chemical change? Options:
  A) Dissoultion of salt in water
  B) Rusting of iron
  C) Melting of ice
  D) Separating a mixture by distillation
  Show Answer
  The correct answer is B .
• Question 1059: H ₂O _(g) + C _(s) → H_2(g) + CO_(g)The oxidizing agent in the reaction above is Options:
  A) CO_(g)
  B) C_(s)
  C) H₂O_(g)
  D) H_(2)(g)
  Show Answer
  The correct answer is C .
• Question 1060: Tartaric acid is used industrially to Options:
  A) make baking powder
  B) make fruit juices
  C) remove rust
  D) dry substance
  Show Answer
  The correct answer is A .