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 71:

  

  In the experiment above, Z can be

  Options:
  A) a solution of sodium dioxonitrate (lll) and ammonium chloride
  B) a solution of lead trioxnitrate (V)
  C) a solution of sodium trioxonitrate (V) and ammonium chloride
  D) concentrated tetraoxosulphate (VI) acid and sodium trioxonitrate (V)
  Show Answer
  The correct answer is C .
• Question 72: Detergents are more advantageous than soaps in hard water districts because Options:
  A) on treatment with hard water they either form soluble calcium salts or do not react with calcium ion
  B) on treatment with hard water they form soluble calcium salts
  C) on treatment with hard water they form sodium salts
  D) on treatment with hard water they are converted into soaps
  E) on treatment with hard water they form more lather than soaps does
  Show Answer
  The correct answer is A .
• Question 73: Deliquescent substances are also? Options:
  A) efflorescent
  B) anhydrous
  C) hygroscopic
  D) insoluble
  Show Answer
  The correct answer is C .
• Question 74: A major factor coonsidered in selecting a suitable method for preparing a simple salt is its Options:
  A) crystalline form
  B) melting point
  C) reactivity with dilute acids
  D) solubility in water
  Show Answer
  The correct answer is D .
• Question 75:

  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 76:

  In the reaction N₂(g) + O(g) ↔ 2NO(g) produced an increase in the total pressure will?

  Options:
  A) cause less nitrogen to be produced in the equilibrium mixture
  B) cause less nitric oxide to be produced in the equilibrium mixture
  C) cause more nitric oxide to be produced in the equilibrium mixture
  D) cause more oxygen to be produced in the equilibrium mixture
  E) have no effect
  Show Answer
  The correct answer is E .
• Question 77: When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as Options:
  A) disintegration
  B) polymerization
  C) cracking
  D) degradation
  E) distillation
  Show Answer
  The correct answer is C .
• Question 78: When H₂S gas is passed into a solution of iron (III) chloride, the colour changes from yellow to green. This is because? Options:
  A) H_(s)S is reduced to S
  B) Fe³⁺ ions are oxidized by H_(s)S
  C) Fe³⁺ ions are oxidized Fe³⁺ ions
  D) Fe³⁺ ions are reduced to Fe²⁺ ions
  Show Answer
  The correct answer is D .
• Question 79: When 50cm² of a saturated solution of sugar of molar mass 342 g at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is Options:
  A) 2.0 mol dm^-3
  B) 3.5 mol dm^-3
  C) 7.0 mol dm^-3
  D) 10.0 mol dm^-3
  Show Answer
  The correct answer is A .
• Question 80:

  Which of these alloys contains copper?

  Options:
  A) solder
  B) steel
  C) permallory
  D) bronze
  Show Answer
  The correct answer is D .