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 2281:

  N_2(g) + 3H_2(g) ↔ 2NH_3(g) ΔH = -90 kJ

  In the equation above, the yield of ammonia can be decreased by

  Options:
  A) increasing the pressure
  B) removing the ammonia as it is formed
  C) increase the temperature
  D) adding a catalyst
  Show Answer
  The correct answer is C .
• Question 2282: If one of the following oxides is heated with hydrogen or carbon using a bunsen burner, it is not reduced to the metal. Which one is it? Options:
  A) Lead oxide
  B) Magnesium oxide
  C) Copper oxide
  D) Tin oxide
  E) Iron oxide
  Show Answer
  The correct answer is B .
• Question 2283: When few drops of concentrated trioxonitrate(V) acid is added to an unknown sample and wanned an intense yellow colouration is observed. The likely functional group present in the sample is Options:
  A) NH₃—C—C=O
  B) CHO
  C) CO
  D) CNH₂
  Show Answer
  The correct answer is A .
• Question 2284: The oxidation state of oxygen in tetraoxosulphate (VI) acid is Options:
  A) -4
  B) -2
  C) +4
  D) -8
  Show Answer
  The correct answer is B .
• Question 2285: Incomplete oxidation of ethanol yields Options:
  A) CH₃COOH
  B) CH₃COCH₃
  C) CH₃CH₂OCH₂CH₃
  D) CH₂CHO
  Show Answer
  The correct answer is D .
• Question 2286: Which of the following statement is true of the electrochemical series? Options:
  A) Electropositivity of metals increase down the series
  B) Electropositivity of non-metals decrease down the series
  C) Electronegativity of non-metals decrease down the series
  D) Electropositivity of metals decreases down the series
  Show Answer
  The correct answer is D .
• Question 2287: In the reaction NH₃ + H⁺ → NH₄⁺, the bond formed results from? Options:
  A) an electron transferred from NH₃ + H⁺
  B) an electron pair donated by NH₃
  C) an electron pair equally shared
  D) an electron pair donated by H⁺
  E) an electron tarnsferred from H⁺ to NH₃
  Show Answer
  The correct answer is B .
• Question 2288:

  In the reactions

  (I) H₂ (g) + 1/2O₂(g) → H₂O(l); ∆H = -286 KJ

  (II) C(s) + O₂g) → CO₂ (g); ∆H = -406 KJ the equations imply that

  Options:
  A) more heat is absorbed in (l)
  B) more heat is absorbed in (ll)
  C) less heat is evolved in (l)
  D) reaction (ll) proceeds faster than (l)
  E) reaction (l) proceeds faster than (ll)
  Show Answer
  The correct answer is C .
• Question 2289:

  What is the state of matter in which particles are widely spaced and move freely with high kinetic energy?

  Options:
  A) Liquid
  B) Solid
  C) Plasma
  D) Gas
  Show Answer
  The correct answer is D .
• Question 2290: A liquid that will dissolve fat is Options:
  A) hydrochloric acid
  B) calcium hydrochloride
  C) kerosene
  D) water
  Show Answer
  The correct answer is C .