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 1251:

  An example of a polysaccharide is?

  Options:
  A) Dextrose
  B) Mannose
  C) Glucose
  D) Starch
  Show Answer
  The correct answer is D .
• Question 1252:

  Suitable reagents for the laboratory preparation nitrogen are

  Options:
  A) sodium dioxonitrate(III) and ammonium chloride
  B) sodium trioxonitrate(V) and ammonium chloride
  C) sodium chloride and ammonium trioxonitrate(V)
  D) sodium chloride and ammonium di-ozonitrate(III)
  Show Answer
  The correct answer is A .
• Question 1253: The enzyme used in the hydrolysis of starch to dextrin and maltose is Options:
  A) amylase
  B) diastatse
  C) invertase
  D) zymase
  Show Answer
  The correct answer is B .
• Question 1254:

  2H${}_2$ + O${}_2$ 2H${}_2$O

  From the equationabove, calculate the volume of unreacted oxygen gas if a mixture of 50cm${}^3$ of hydroden and 75cm${}^3$ of oxygen are involved

  Options:
  A) 85cm${}^3$
  B) 50cm${}^3$
  C) 125cm${}^3$
  D) 55cm${}^3$
  Show Answer
  The correct answer is B .
• Question 1255: The modern process of manufacturing steel for iron is by Options:
  A) treatment with acids
  B) oxidation
  C) blast reduction
  D) treatment with alkanal
  Show Answer
  The correct answer is C .
• Question 1256:

  1.00 g of the oxide of metal X (atomic mass = 64) gave 0.80 g of the metal when reduced with hydrogen.

  The formula of the oxide is?

  Options:
  A) X₂O
  B) XO
  C) XO₂
  D) X₂O₃
  E) X₃O₄
  Show Answer
  The correct answer is B .
• Question 1257: The reaction 3C(s) + 2Fe₂O₃(s) = 4Fe(s) + 3CO₂(g): $\mathrm{\Delta }$H =46.0 kJ is Options:
  A) isothermic
  B) adiabatic
  C) isobaric
  D) endothermic
  E) exothermic
  Show Answer
  The correct answer is D .
• Question 1258:

  An aqueous solution of a metal salt, M. gives a white precipitate with NaOH which dissolves in excess NaOH. With aqueous ammonia, the solution of M also gives a white precipitate which dissolves in excess ammonia Therefore the cation in M is

  Options:
  A) Zn
  B) Ca
  C) Al
  D) Po
  Show Answer
  The correct answer is A .
• Question 1259:

  The substance often used for vulcanization of rubber is?

  Options:
  A) Chlorine
  B) Hydrogen peroxide
  C) Sulphur
  D) Tetraoxosulphate(vi) acid
  Show Answer
  The correct answer is C .
• Question 1260: 5 block elements of the periodic table one made up of Options:
  A) groups 1, 2, 3
  B) groups 1, and 2
  C) group 3
  D) group 3 to 7
  Show Answer
  The correct answer is B .