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 641:

  Which of the following is the best starting material for the preparation of oxygen? Heating of trioxonitrate (v) with

  Options:
  A) Pb
  B) Zn
  C) Ca
  D) Na
  Show Answer
  The correct answer is A .
• Question 642: In a water body, too much sewage leads to Options:
  A) a decrease in the temperature of the water which cause in death of aquatic animals
  B) an increase in the number of aquatic animals in the water
  C) an increase in the bacterial population which reduces the level of oxygen in the water
  D) a decrease in the bacterial population which increases the level of oxygen in the water
  Show Answer
  The correct answer is C .
• Question 643: The impurities formed during the laboratory preparation of chlorine gas are removed by Options:
  A) H₂O
  B) NH₃
  C) H₂SO₄
  D) HCl
  Show Answer
  The correct answer is A .
• Question 644:

  A given amount of gas occupies 10.0dm5 at 4atm and 273°C. The number of moles of the gas present is [Molar volume of gas at s.t.p = 22.4dm${}^3$]

  Options:
  A) 0.89 mol
  B) 1.90 mol
  C) 3.80 mol
  D) 5.70 mol
  Show Answer
  The correct answer is A .
• Question 645:

  Diamond is a bad conductor of electricity because its bonding electrons are used in

  Options:
  A) crystal lattice formation
  B) covalent bond formation
  C) metallic bond formation
  D) coordinate bond formation
  Show Answer
  The correct answer is B .
• Question 646: Which among the elements 1. Carbon 2. Oxygen 3. Copper 4. Bromine 5. Zinc, will NOT react with either water or steam? Options:
  A) 1 and 2
  B) 2 and 3
  C) 3 and 4
  D) 1, 2, and 3
  E) 2, 3, and 5
  Show Answer
  The correct answer is B .
• Question 647: Which of the following gases has a characteristic pungent smell, turns red litmus paper blue and forms dense white fumes with hydrogen chloride gas? Options:
  A) N₂
  B) N₂O
  C) CI₂
  D) NH₃
  Show Answer
  The correct answer is D .
• Question 648: How many electrons are in the L shell of ³¹₁₅P? Options:
  A) 5
  B) 8
  C) 18
  D) 2
  Show Answer
  The correct answer is B .
• Question 649: A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is Options:
  A) O₂
  B) NO
  C) SO₂
  D) NH₃
  E) CO₂
  Show Answer
  The correct answer is C .
• Question 650: A gas occupies 30.0 dm³ at S.T.P. What volume would it occupy at 91^oC and 380 mm Hg? Options:
  A) 20. 0dm³
  B) 40.0dm³
  C) 60. 0dm³
  D) 80. 0dm³
  E) 100. 0dm³
  Show Answer
  The correct answer is D .