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 1491: Which of the following derivatives of nitrogen affords an aqueous solution having a pH of less that 7? Options:
  A) N₂O
  B) NO
  C) NO₂
  D) NaNO₃
  E) NH₃
  Show Answer
  The correct answer is C .
• Question 1492: A mixture of ethanol, sodium dichromate, and water is allowed to drop gradually into a boiling solution containing one part concentrated H₂SO
  ₄ and the liberate gas is collected by cooling it with ice water to give a liquid. This liquid is? Options:
  A) ethanoic acid
  B) acetaldehyde
  C) ethyl acetate
  D) methanol
  E) ethylene
  Show Answer
  The correct answer is A .
• Question 1493: According to the kinetic theory an absence in temperature causes the kinetic energy of particles to Options:
  A) decrease
  B) increase
  C) remain constant
  D) be zero
  Show Answer
  The correct answer is C .
• Question 1494: In the production of soap, concentrated sodium chloride solution is added to Options:
  A) increase the solubility of soap
  B) decrease the solubility of the soap
  C) saponify the soap
  D) emulsify the soap
  Show Answer
  The correct answer is B .
• Question 1495:

  4g each of aluminium foil and aluminium powder were introduced respectively into flasks P and Q.

  Flask P was treated with warm bench sodium hydroxide and all the aluminium dissolved in one hour. Flask Q was treated with cold sodium hydroxide and all the aluminium dissolved in 10 minutes. What was responsible for Q reacting faster than P?

  Options:
  A) There were more aluminium atoms in Q than P
  B) The heat given off in retarded the reaction
  C) Q generated more pressure than P during the reaction
  D) P generated more pressure than Q
  E) Q has a greater surface area for the reaction than P
  Show Answer
  The correct answer is E .
• Question 1496: If an element has the electronic configuration 1s ² 2s² 2p³ 3s² 3p⁴, it is Options:
  A) a metal
  B) an alkaline earth metal
  C) an s-block element
  D) a p-Block element
  E) a transition element
  Show Answer
  The correct answer is D .
• Question 1497: Carbohydrates are large molecules with the molecular formula C _x (H₂O)_y. In which of the following pairs is x not equal to y? Options:
  A) glucose and starch
  B) maltose and starch
  C) sucrose and fructose
  D) maltose and starch
  Show Answer
  The correct answer is A .
• Question 1498: A metal is extracted from its ore by the electrolysis of its molten chloride and it displaces lead from lead (ll) trioxonitrate (V) solution. The metal is Options:
  A) copper
  B) aluminium
  C) zinc
  D) sodium
  Show Answer
  The correct answer is D .
• Question 1499:

  If 100 cm³ of oxygen pass through a porous plug in 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is?

  (O = 16, H = 1)

  Options:
  A) 10.0 s
  B) 12.5 s
  C) 17.7 s
  D) 32.0 s
  Show Answer
  The correct answer is B .
• Question 1500: When each of the nitrates of Potassium, Magnesium and iron is heated, Options:
  A) all the nitrates decompose to their oxides
  B) the nitrate of magnesium gives the nitrite and oxygen
  C) the nitrates of iron magnesium and iron give the oxides
  D) the nitrate of iron gives the nitrite and oxygen
  E) the nitrate of the magnesium is not decomposed
  Show Answer
  The correct answer is C .