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 721: The movement of liquid molecules from the surface of the liquid to the gaseous phase above it is known as? Options:
  A) Brownian movement
  B) condensation
  C) evaporation
  D) liquefaction
  Show Answer
  The correct answer is C .
• Question 722: Pure solvents are obtained by Options:
  A) Distillation
  B) Condensation
  C) Extraction
  D) Evaporation
  Show Answer
  The correct answer is A .
• Question 723: In which of the following reactions has the oxidation number of nitrogen increased? Options:
  A) 2NO_(g) + Br_2(l) → 2NOBr_(l)
  B) 2NO_(g) + O_2(g) → 2NO_2(g)
  C) FeSO_4(aq) + NO_(g) → Fe(NO)SO_4(s)
  D) 2NO(g) + Cl_2(g) → 2NOCl(l)
  Show Answer
  The correct answer is B .
• Question 724: When H₂S gas is passed into a solution of iron (III) chloride, the colour changes from yellow to green. This is because? Options:
  A) H_(s)S is reduced to S
  B) Fe³⁺ ions are oxidized by H_(s)S
  C) Fe³⁺ ions are oxidized Fe³⁺ ions
  D) Fe³⁺ ions are reduced to Fe²⁺ ions
  Show Answer
  The correct answer is D .
• Question 725: The formula of a compound formed in a reaction between a trivalent metal M and a tetravalent non-metal X is~? Options:
  A) MX
  B) M₃X₄
  C) M₄X₃
  D) M₃X₂
  Show Answer
  The correct answer is C .
• Question 726: When chlorine Is passed into water and the resulting solution exposed to sunlight, the product formed are Options:
  A) Chlorine gas and hydrogen
  B) Oxygen and oxochlorate (I) acid
  C) Chlorine gas and oxochlorate (I) acid
  D) Hydrochloric acid and oxygen
  Show Answer
  The correct answer is D .
• Question 727:

  Which organic compound is responsible for the characteristic aroma of fruits?

  Options:
  A) Alkane
  B) Alkyne
  C) Ester
  D) Amine
  Show Answer
  The correct answer is C .
• Question 728: which of these metals CANNOT replace hydrogen from alkaline solutions? Options:
  A) Aluminium
  B) Zinc
  C) Tin
  D) Iron
  Show Answer
  The correct answer is A .
• Question 729:

  

  In the experiment above, a current was passed for 10 minutes and 0.63g of copper was found to be deposited on the cathode of CuSO₄ cells. The weight of silver deposited on the cathode og AgNO³ cell during the same period would be? [Cu = 63, Ag = 108]

  Options:
  A) 0.54g
  B) 1.08g
  C) 1.62g
  D) 2.16g
  E) 3.24g
  Show Answer
  The correct answer is B .
• Question 730:

  How many grams of H₂SO₄ are necessary for the preparation of 0.175 dm³ of M 6.00 M H₂SO₄?

  (S = 32.06, O = 16.00 H = 1.00)

  Options:
  A) 206.0 g
  B) 103.0 g
  C) 98.1 g
  D) 51.5 g
  Show Answer
  The correct answer is B .