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:

  A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as __________.

  Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 192: A characteristic reaction of the compounds with the general formula C_nH_2n is Options:
  A) Esterification
  B) Polymerization
  C) Decarboxylation
  D) Substitution
  Show Answer
  The correct answer is B .
• Question 193:

  A colourless organic compound X was burnt in excess air to give two colourless and odourless gases, Y and Z, as products. X does not decolorize blue bromine vapour, Y turns lime milky while Z gives a blue colour with copper (ll) tetraoxosulphate (IV).

  Compound X is?

  Options:
  A) an alkene
  B) an alkane
  C) an alkyne
  D) tetrachloromethane
  E) dichloromethane
  Show Answer
  The correct answer is B .
• Question 194:

  10g of a solid is in equilibrium with its own vapour.

  When 1 g of a small amount of solid is added, the vapour pressure?

  Options:
  A) remains the same
  B) drops
  C) increases by 1%
  D) increases by 99%
  Show Answer
  The correct answer is B .
• Question 195:

  A current of 10.0A was passed for 1 hour through a solution of copper (ll) sulphate between the copper electrodes. Which of the following observation would be correct?

  (1 Faraday = 96,500 coulobms) (i) 0.186 mole of copper is dissolved from the anode. (ii) 0.372 mole of copper is deposited on the cathode. (iii) the original Cu²⁺ ion concentration of the solution remains unchanged. (iv) the original Cu²⁺ ion concentration of the solution decreases.

  Options:
  A) i and ii
  B) i and iii
  C) i and iv
  D) ii and iii
  E) ii and iv
  Show Answer
  The correct answer is B .
• Question 196: The fuming of kettles is caused by the presence in the water of Options:
  A) Calcium tetraoxosulphate (VI)
  B) Calcium hydrogentrioxocarbonate (IV)
  C) Calcium hydroxide
  D) Calcium trioxocarbonate (IV)
  Show Answer
  The correct answer is B .
• Question 197:

  How many atoms are present in 6.0g of magnesium? [Mg = 24, N.A = 6.02 x 10 ${}^{23}$mol]

  Options:
  A) 1.20 x 10${}^{22}$
  B) 2.4 x 10${}^{22}$
  C) 1.51 x 10${}^{22}$
  D) 3.02 x 10${}^{22}$
  Show Answer
  The correct answer is C .
• Question 198: Which of the following are made by the process of polymerization? Options:
  A) Nylon and soap
  B) Nylon and artificial rubber
  C) Soap and butane
  D) Margarine and nylon
  Show Answer
  The correct answer is B .
• Question 199: 30 cm³ of 0.1 M Al (NO₃)₃ SOLUTION IS RECTED WITH 100cm³ of 0.15M of NaOH solution. Which reactant is in excess, and by now much ? Options:
  A) NaOH solution by 70 cm³
  B) NaOH solution, by 60 cm³
  C) NaOH solution by 40 cm³
  D) Al(NO₃)₃ solution by 20 cm³
  E) Al(NO₃)₃ solution by 10 cm³
  Show Answer
  The correct answer is C .
• Question 200: Calcium hydroxide and ammonium chloride when heated together will give an important product. This compound may be obtained dry by Options:
  A) dissolving it in water, recrystallizing it and then drying in the oven
  B) passing it through a concentrated aqueous solution of sodium hydroxide
  C) passing it through calcium oxide
  D) passing it through concentrated sulphuric acid
  E) passing it through anhydrous calcium choride
  Show Answer
  The correct answer is C .