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 1611: 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 1612:

  MnO_4(aq) + 8H + 5Fe²⁺ $\to$ Mn²⁺_(aq) + 5Fe³⁺_(aq) + H₂O.

  The oxidation number of manganese in the above reaction changed from

  Options:
  A) +7 to +2
  B) +6 to +2
  C) +5 to +2
  D) +4 to +2
  Show Answer
  The correct answer is A .
• Question 1613:

  Which of the following properties increases from left to right along the period but decreases down the group in the Periodic Table?

  I. Atomic Number   ii. Ionization energy  iii. Metallic character  iv. Electron affinity

  Options:
  A) ii and iii only
  B) ii and iv only
  C) iii and iv only
  D) i and ii only
  Show Answer
  The correct answer is B .
• Question 1614:

  A 'breath test' used by traffic police to check drunken driving uses?

  Options:
  A) Tumeric on filter paper
  B) Silica gel coated with saliva nitrate
  C) Potassium permanganate-sulphuric acid
  D) Potassium dichromatic-sulphuric acid
  Show Answer
  The correct answer is D .
• Question 1615:

  Cu²⁺_(aq) + 4NH_3(g) ↔ [Cu(NH₃)₄]²⁺_(aq)

  In the reaction above, what is the effect of precipitating Cu²⁺_(aq) as CuS_(s)?

  Options:
  A) NH_3(g) concentration will decrease
  B) more NH_3(g)
  C) The equilibrium will shift to the right
  D) There will be no effect
  Show Answer
  The correct answer is C .
• Question 1616:

  (I). 3CuO(s) + 2NH3(g) -----> 3Cu(s) + 3H2O(l) + N2(g) 

  (II). 2NH3(g) + 3Cl2(g) -----> 6HCl(g) + N2(g) 

  (III). 4NH3(g) + 3O2(g) -----> 6H2O(l) + N2(g) 

  The reactions represented by the equations above demonstrate the

  Options:
  A) basic properties of ammonia
  B) acidic properties of ammonia
  C) reducing properties of ammonia
  D) oxidizing properties of ammonia
  Show Answer
  The correct answer is C .
• Question 1617: Which of the following is an example of a mixture? Options:
  A) Common salt
  B) Blood
  C) Sand
  D) Washing soda
  Show Answer
  The correct answer is B .
• Question 1618:

  Al₂O_3(s) + 3H₂SO_4(aq) → Al₂(SO_4(aq)) + 3H_2(I)O

  Al₂O_3(s) + 2NaOH_(aq)) + 3H_2(I)O → 2NaAl(OH)_4(aq)).

  We can conclude from the equations above that Al₂O_3(s) is?

  Options:
  A) an acidic oxide
  B) an amphoteric oxide
  C) a basic oxide
  D) a neutral oxide
  Show Answer
  The correct answer is B .
• Question 1619: Some properties of chemical substances are mentioned below... i. sour taste ii. slippery touch iii. yields alkaline gas with ammonium salt iv. has pH less than 7 v. turns phenolphthalein pink.Which of the above are NOT typical properties of alkalis? Options:
  A) i, iv and v
  B) iv and v
  C) i and iv
  D) ii and v
  E) ii, iii and iv
  Show Answer
  The correct answer is C .
• Question 1620: Which of the following metals can be prepared in samples by the thermal decomposition of their trioxonitrate (V) salts? Options:
  A) Copper and mercury
  B) Silver and copper
  C) Mercury and silver
  D) Magnesium and mercury
  Show Answer
  The correct answer is C .