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 1291:

  What is the chemical name for the compound CuCO${}_3$?

  Options:
  A) Copper (iii) carbonate
  B) Copper (ii) carbonate
  C) Copper (i) carbonate
  D) Copper
  Show Answer
  The correct answer is B .
• Question 1292:

  

  The diagram above is the solubility curve of a solute, X. Find the amount of X deposited when 500cm³ of a solution of X is cooled from 60^oC to 20^oC.

  Options:
  A) 0.750 mole
  B) 0.950 mole
  C) 2.375 moles
  D) 4.750 moles
  Show Answer
  The correct answer is A .
• Question 1293: 2.85g of an oxide of copper gave 2.52g of copper on reduction and 1.90g of another oxide gave 1.52g of copper on reduction. The data above illustrates the law of? Options:
  A) constant composition
  B) conservation of mass
  C) reciprocal proportions
  D) multiple proportions
  Show Answer
  The correct answer is D .
• Question 1294: If chlorine gas is bubbled into water and then this yellowish-green coloured solution is exposed to bright sunlight for a while Options:
  A) the solution will give out chlorine gas and hydrogen chloried gas
  B) the solution will produce chlorine gas and oxygen
  C) the solution will give out solution will producing hypochloric acid
  D) the solution is decomposed giving out oxygen, hydrogen and chlorine
  E) the solution will give out oxygen gas leaving behind aqueous hydrochloric acid
  Show Answer
  The correct answer is E .
• Question 1295:

  3Cu_(s) + 8HNO_3(aq) 3Cu(NO₃)_2(aq) + 4H₂O_(l) + 2NO_(g)

  In the equation above, copper is

  Options:
  A) an electron acceptor
  B) a base
  C) an oxidizing agent
  D) a reducing agent
  Show Answer
  The correct answer is D .
• Question 1296: The empirical formula of an oxide of nitrogen containing 30.4 per cent of nitrogen is (N=14.0,O=16.0) Options:
  A) N₂O₂
  B) NO
  C) NO₂
  D) N₂O
  E) N₂O₃
  Show Answer
  The correct answer is C .
• Question 1297:

  Sodium sulphate decahydrate (Na₂SO₄.10 H₂O) on exposure to air loses all its water of crystallization.

  The process of loss is known as

  Options:
  A) efflorescence
  B) hygroscopy
  C) deliquescence
  D) effervescence
  E) dehydration
  Show Answer
  The correct answer is A .
• Question 1298:

  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.

  Compound W is

  Options:
  A) a soap
  B) an oil
  C) an alkane
  D) an ester
  E) sucrose
  Show Answer
  The correct answer is D .
• Question 1299: The partial pressure of oxygen in a sample of air is 452mmHg and the total pressure is 780mmHg. What is the mole fraction of oxygen? Options:
  A) 0.203
  B) 0.579
  C) 2.060
  D) 5.790
  Show Answer
  The correct answer is B .
• Question 1300:

  

  In the solubility curve above, water at 98^oC is saturated with KCL and KCIO₃ What is the percentage of KCL impurity in the crystals formed when the solution is cooled to 30 ^oC?

  Options:
  A) 51.5
  B) 45.5
  C) 34.5
  D) 26.5
  Show Answer
  The correct answer is C .