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 191: Argon is used in gas-filled electric lamp because it helps to? Options:
  A) prevent the reduction of the lamp fillaments
  B) prevent oxidation of the lamp fillaments
  C) make the lamp fillament glow brightly
  D) keep the atmosphere in the lamp inert
  Show Answer
  The correct answer is C .
• Question 192: A given mass of gas occupies 2 dm³ at 300k. At what temperature will its volume be doubled keeping the pressure constant? Options:
  A) 400k
  B) 480k
  C) 550k
  D) 600k
  Show Answer
  The correct answer is D .
• Question 193:

  

  The IUPAC name for

  Options:
  A) 1-methlpentane
  B) 3-methylbutane
  C) 2-methylbutane
  D) 1-dimethylpropane
  E) 2-methylpentane
  Show Answer
  The correct answer is C .
• Question 194: A molar solution of caustic soda is prepared by dissolving Options:
  A) 40 g NaOH in 100 g of water
  B) 40 g NaOH in 1000 g of water
  C) 20 g NaOH in 500 of solution
  D) 20 g NaOH in 1000 g of solution
  E) 2o g NaOH in 80 g of solution
  Show Answer
  The correct answer is B .
• Question 195: The least easily oxidized of the metals below is Options:
  A) Ca
  B) Na
  C) Zn
  D) Al
  Show Answer
  The correct answer is D .
• Question 196:

  At 2.0 atm pressure, the volume of a gas is 4.0 L. If the pressure is reduced to 1.0 atm while keeping the temperature constant, what will be the new volume of the gas?

  Options:
  A) 2.0 L
  B) 6.0 L
  C) 8.0 L
  D) 4.0 L
  Show Answer
  The correct answer is C .
• Question 197: The molecular formula of a common organic laboratory anaesthetic is Options:
  A) CHCl₃
  B) CHI₃
  C) CCl₄
  D) CHF₃
  Show Answer
  The correct answer is A .
• Question 198: Which is the temperature of a given mass of a gas initially at 0°C and 9 atm, if the pressure is reduced to 3 atm at constant volume? Options:
  A) 91K
  B) 182K
  C) 273K
  D) 819K
  Show Answer
  The correct answer is A .
• Question 199: Chlorine gas is prepared in the laboratory by Options:
  A) adding concentrated hydrochloric acid to solid manganese (IV) oxide
  B) aciding concentrated tetraoxosulphate (VI) acid to solid sodium chloride
  C) dropping concentrated hydrochloric acid onto potassium tetraoxomanganate (VI) crystals
  D) aciding concentrated tetraoxosulphate (VI) acid to hydrochloric acid
  Show Answer
  The correct answer is A .
• Question 200:

  MnO^-_4(aq) + Y + 5Fe²⁺_(aq) → Mn²⁺_(aq) + 5Fe²⁺_(aq) + 4H₂O^(l)

  In the equation above, Y is

  Options:
  A) 5H⁺_(aq)
  B) 4H⁺_(aq)
  C) 10H⁺_(aq)
  D) 8H⁺_(aq)
  Show Answer
  The correct answer is D .