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 341:

  

  The compound above is

  Options:
  A) glycol
  B) primary alkanol
  C) secondary alkanol
  D) tertiary alkanol
  Show Answer
  The correct answer is C .
• Question 342:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  Reaction of X with yeast forms the basis of the

  Options:
  A) plastic industry
  B) textile industry
  C) brewing industry
  D) soap industry
  E) dyeing industry
  Show Answer
  The correct answer is C .
• Question 343: 3Cl₂ + 2NH₃ $\to$ N₂ + 6HCl. In the above reaction, ammonia acts as Options:
  A) a reducing agent
  B) an oxidizing agent
  C) an acid
  D) a catalyst
  E) a dry agent
  Show Answer
  The correct answer is A .
• Question 344: Deliquescent substance are used for Options:
  A) Cooling
  B) Wetting
  C) Melting
  D) Drying
  Show Answer
  The correct answer is D .
• Question 345: An isomer of C₅H₁₂ is Options:
  A) Butane
  B) 2 – methylbutane
  C) 2 – methylpropane
  D) 2 – ethylbutane
  Show Answer
  The correct answer is B .
• Question 346: Which of the following is an electrolyte? Options:
  A) alcohol
  B) sodium ethanoate
  C) solid potassium hydroxide
  D) mercury
  Show Answer
  The correct answer is B .
• Question 347: The decarboxylation of ethanoic acid will produce carbon (IV)oxide and Options:
  A) methane
  B) ethane
  C) propane
  D) butane
  Show Answer
  The correct answer is A .
• Question 348:

  Which of the following is a form of calcium carbonate?

  I. limestone
  II. marble
  III. chalk
  Iv. egg-shells

  Options:
  A) I only
  B) I, II and IV
  C) I and II only
  D) I, II, III, and IV
  Show Answer
  The correct answer is D .
• Question 349:

  Mg²⁺_(aq) + 2e^->_(aq) → Mg_(s)E°_(volts) = 2.370

  Zn²⁺_(aq) + 2e^->_(aq) → Zn_(s)E°_(volts) = -0.763

  Cds²⁺_(aq) + 2e^->_(aq) → Cd_(s)E°_(volts) = 0.403

  Cu²⁺_(aq) + 2e^->_(aq) → Cu_(s)E°_(volts) = 0.340

  In the electrochemical series above, the strongest reducing agents is?

  Options:
  A) Cu _(s)
  B) Cd_(s)
  C) Znsub>(s)
  D) Mg_(s)
  Show Answer
  The correct answer is D .
• Question 350: Which of the following will change when a catalyst is added to a chemical reaction? Options:
  A) The activation energy
  B) The potential energy of the reactants
  C) The heat of the reaction
  D) the potential energy of the product
  Show Answer
  The correct answer is A .