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 1271:

  

  The elections or two atoms Y and Z are arranged in shes as shown above. The bond formed between the atoms of Y and Z is

  Options:
  A) ionic
  B) convalent
  C) dative
  D) metallic
  Show Answer
  The correct answer is B .
• Question 1272:

  H_2(g) + Br_2(g) → 2HBr_(g)

  The above reaction is carried out at 25^oC. ΔH is -72 kJ mol^-1 and ΔS is - 106 J mol^-1K^-1, the reaction will

  Options:
  A) not proceed spontaneously at the given
  B) proceed spontaneously at the given temperature
  C) proceed in the reverse direction at the given temperature
  D) proceed spontenously at lower temperature
  Show Answer
  The correct answer is A .
• Question 1273: When excess ethanol is heated to 145 ^oC in the presence of concentrated sulphuric acid, the product is Options:
  A) diethyl ether
  B) ethyne
  C) diethyl sulphate
  D) acetone
  E) ethanoic acid
  Show Answer
  The correct answer is A .
• Question 1274:

  Which of the following pairs cannot be represented with a chemical formula?

  Options:
  A) air and bronze
  B) bronze and sodium chloride
  C) copper and sodium chloride
  D) caustic soda and washing soda
  Show Answer
  The correct answer is A .
• Question 1275: In the reaction of oxygen with hydrogen to produce water, which of the following statements is true? Options:
  A) One atom of hydrogen reacts with two atoms of oxygen to give one molecule of water
  B) Two atoms of hydrogen react with two atoms of oxygen to give two molecules of water
  C) One molecule of oxygen reacts with one molecule of hydrogen to give two molecules of water
  D) One molecule of hydrogen reaccts with two molecules of oxygen to give three molecules of water
  E) One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
  Show Answer
  The correct answer is E .
• Question 1276: Iron galvanized with zinc is cathodically protected from corrosion. This is because? Options:
  A) zinc has a more positive oxidation potential than iron
  B) zinc has less positive oxidation potential than iron
  C) bith have the same oxidation potential
  D) zinc is harder than iron
  Show Answer
  The correct answer is B .
• Question 1277: The substance that is used in the steel industry for the removal of carbon. Sulphur and phosphorus impurities from pig iron is Options:
  A) oxygen
  B) chlorine
  C) nitrogen
  D) hydrogen
  Show Answer
  The correct answer is A .
• Question 1278:

  What volume of oxygen measured at s.t.p would be liberated on electrolysis by 9650 coulombs of electricity?

  (Molar volume of gas = 22.4 dm³, F = 96,500 C mol^-)

  Options:
  A) 22.4 dm³
  B) 11.2 dm³
  C) 1.12 dm³
  D) 0.560 dm³
  Show Answer
  The correct answer is D .
• Question 1279: Which of the following compounds will give a precipitate with an aqueous ammoniacal solution of copper (l) chloride? Options:
  A) CH₃ = CHCH₃
  B) CH₃ ≡ CCH₃
  C) HC = C-CH₂CH₃
  D) CH₂ = CH-CH = CH₂
  Show Answer
  The correct answer is B .
• Question 1280:

  In the extraction of iron, hot air is introduced into the blast furnacethrough?

  Options:
  A) valves
  B) open-hearths
  C) arcs
  D) tuyeres
  Show Answer
  The correct answer is D .