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 1711: The products of the thermal decomposition of ammonium trioxonitrate (V) are Options:
  A) NO ₂ and oxygen
  B) NH₃ and oxygen
  C) nitrogen and water
  D) N₂O and water
  Show Answer
  The correct answer is D .
• Question 1712: Which of the following will produce the greatest increase in the rate of the chemical reaction represented by the equation Na₂S₂O_3(aq) + 2HCl_(aq) → 2NaCI_(aq) + H₂O_(I) + SO_2(g) + S_(g)? Options:
  A) A decrease in temperature and an increase in the concentration of the reactants
  B) An increase in the temperature and a decrease in the cocentration of the reactants
  C) An increase in temperature and an increase in the concentration of the reactants
  D) A decrease in the temperature and a decrease in the concentration of the reactants
  Show Answer
  The correct answer is C .
• Question 1713: The property of concentrated H₂SO₄ that makes it suitable for preparing HNO₃ is its Options:
  A) boiling point
  B) density
  C) oxidizing properties
  D) dehydrating properties
  Show Answer
  The correct answer is C .
• Question 1714:

  The metal used to recover copper from a solution of copper sulphateis?

  Options:
  A) Na
  B) Ag
  C) Hg
  D) Fe
  Show Answer
  The correct answer is D .
• Question 1715: 35 cm³ of hydrogen was sparked with 12 cm³ of oxygen at 110°C and 760mm Hg to produce steam. What percentage of the total volume of gas left after the reaction is hydrogen? Options:
  A) 11%
  B) 31%
  C) 35%
  D) 69%
  Show Answer
  The correct answer is B .
• Question 1716: The air around a petroleum refinery is most likely to contain? Options:
  A) CO₂, SO₃ and N₂O
  B) CO₂, CO and N₂O
  C) SO₂, CO and NO₂
  D) PH₃ H₂O and CO₂
  Show Answer
  The correct answer is C .
• Question 1717:

  The only metal that is anti-bacterial is?

  Options:
  A) Iron
  B) Sodium
  C) Alluminium
  D) Copper
  Show Answer
  The correct answer is D .
• Question 1718:

  The IUPAC nomenclature of the compound

  H${}_3$C - CH(CH${}_3$) - CH(CH${}_3$) - CH${}_2$ - CH${}_3$

  Options:
  A) 3,4- dimethylhexane
  B) 2,3- dimethyl pentane
  C) 2- ethyl hexane
  D) 2,3- dimethylhexane
  Show Answer
  The correct answer is B .
• Question 1719: The number of atoms of chlorine present in 5.85g of NaCl is [Avogaro's Number = 6.02 x 10²³] Options:
  A) 6.02 x 10²²
  B) 5.85 x 10²³
  C) 6.02 x 10²³
  D) 5.85 x 10²⁴
  Show Answer
  The correct answer is A .
• Question 1720: The solubility of copper (II) tetraoxosulphate (Iv) is 75g in 100g of water at 100°C and 25g in 100g of water at 30°C. What mass of the salt would crystallize, if 50g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C ? Options:
  A) 57.5
  B) 42.2
  C) 28.6
  D) 14.3
  Show Answer
  The correct answer is D .