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 501:

  Which of the following gases will rekindle a brightly splint?

  Options:
  A) NO${}_2$
  B) NO
  C) N${}_2$O
  D) CL${}_2$
  Show Answer
  The correct answer is C .
• Question 502: Steam changes the colour of anhydrous cobalt (II) chloride from Options:
  A) blue to pink
  B) white to red
  C) white to green
  D) blue to white
  Show Answer
  The correct answer is A .
• Question 503: An acid is said to be weak if? Options:
  A) its ions are so completely dissociated that they easily drift apart
  B) the acid is not corrosive
  C) the acid has low specific gravity
  D) its ions move very slowly when in solution
  E) its ions are incompletely dissociated
  Show Answer
  The correct answer is E .
• Question 504:

  C₂H_4(g) + H_2(g) → C₂H_6(g) ΔH = -137kJ mol_-1

  The reaction represented above is

  Options:
  A) exothermic
  B) spontaneous
  C) endothermic
  D) in equilibrium
  Show Answer
  The correct answer is A .
• Question 505:

  

  The functional groups present in the compound above are

  Options:
  A) Alkene and halo-group
  B) Hydroxyl and chloro-group
  C) Alkene and chloro-group
  D) Hydroxyl and halo-group
  Show Answer
  The correct answer is B .
• Question 506: The hydroxyl ion concentrated, (OH^-), in a solution of sodium hydroxide of pH 10.0 is? Options:
  A) 10^-10 mol dm^-3
  B) 10^-6 mol dm^-3
  C) 10^-4 mol dm^-3
  D) 10^-2 mol dm^-3
  Show Answer
  The correct answer is C .
• Question 507:

  1.00 g of the oxide of metal X (atomic mass = 64) gave 0.80 g of the metal when reduced with hydrogen.

  The formula of the oxide is?

  Options:
  A) X₂O
  B) XO
  C) XO₂
  D) X₂O₃
  E) X₃O₄
  Show Answer
  The correct answer is B .
• Question 508:

  On the basis of the electrochemical series, which of these ions will show the greater tendency to be discharged at the cathode in an electrolytic cell

  Options:
  A) cu${}^{2+}$
  B) sn${}^{2+}$
  C) fe${}^{2+}$
  D) zn${}^{2+}$
  Show Answer
  The correct answer is A .
• Question 509:

  

  The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X_(g) + Y_(g) → XY_(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X_(g) + Y_(g)

  Options:
  A) 300, 500
  B) 500, 300
  C) -300, -500
  D) -500, -300
  Show Answer
  The correct answer is A .
• Question 510:

  Addition of sodium chloride to water to form a solution would lead to?

  Options:
  A) increase in freezing point and increase the boiling point
  B) increase in freezing point and decrease the boiling point
  C) decrease in freezing point and decrease the boiling point
  D) decrease in freezing point and increase the boiling point
  Show Answer
  The correct answer is D .