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 851:

  A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as __________.

  Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 852: An increase in entropy can best be illustrated by Options:
  A) mixing of gases
  B) freezing of water
  C) the condensation of vapour
  D) solidifying candle wax
  Show Answer
  The correct answer is A .
• Question 853: When a piece of charcoal enclosed in a cylinder containing air is ignited Options:
  A) the toatl volume of air is increased
  B) the relative amount of oxygen present is increased
  C) the relative amount of nitrogen present is decreased
  D) the relative amount of carbondioxide present is increased
  E) the ratio of oxygen to nitrogen in the system is increased
  Show Answer
  The correct answer is D .
• Question 854:

  2H₂S_(g) + SO_2(g) + H₂O_(l) → 3S_(s) + 3H₂O_(l)..........(I)

  3CuO_(s) + 2NH_3(g) → 3Cu_(s) + 3H₂O_(l) + N_2(g).........(II)

  In the equations above, the oxidizing agent (I) and the reducing agent in (II) respectively are?

  Options:
  A) H₂S and NH₃
  B) SO₂ and CuO
  C) SO₂ and NH₃
  D) H₂S and CuO
  Show Answer
  The correct answer is C .
• Question 855: A gas exerts pressure on its container because Options:
  A) some of its molecules are moving faster than others
  B) of the collision of the molecules with each other
  C) of the mass of the molecules of gas
  D) the molecules of a gas colide with the walls of the container
  Show Answer
  The correct answer is D .
• Question 856:

  The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?

  Options:
  A) carbon-14
  B) phosphorus-32
  C) cobalt
  D) iodine-131
  Show Answer
  The correct answer is C .
• Question 857: Which of the following statements is true of sulphur (IV) oxide? Options:
  A) It forms tetraoxosulphate (VI) acid with water
  B) It is an odourless gas
  C) It is an acid hybride
  D) It forms white precipitate with acidified barium chloride
  Show Answer
  The correct answer is C .
• Question 858: If atom X with six electrons in its outermost shell combines with atom Y with one electron in its outermost shell to form an ionic compound, then? Options:
  A) six atoms of X will combine with one of Y
  B) two atoms of X will combine with six of Y
  C) one atom of X will combine with two of Y
  D) two atoms of X will combine with one of Y
  E) one atom of X will combine with six of Y
  Show Answer
  The correct answer is C .
• Question 859: The formula for ethyl butanoate is Options:
  A) C₃H₇COOC₂H₅
  B) C₂H₅COOC₃H₇
  C) C₄H₉COOC₂H₅
  D) C₂H₅COOC₄H₉
  Show Answer
  The correct answer is A .
• Question 860: Iron is often galvanized in order to Options:
  A) Make it more malleable
  B) Remove the impurities unit
  C) Protect it against corrosion
  D) Render it passive
  Show Answer
  The correct answer is C .