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 771: A reaction takes places spontaneously if?
  Options:
  A) ∆G = O
  B) ∆S < O and ∆H > O
  C) ∆H < T ∆S
  D) ∆G > O
  Show Answer
  The correct answer is C .
• Question 772:

  When a substance is oxidized, it

  Options:
  A) Loses electrons
  B) Gains oxygen atoms
  C) Gains electrons
  D) Loses protons (H+ ions)
  Show Answer
  The correct answer is A .
• Question 773: How many cations will be produced from a solution of potassium aluminium tetraoxosulphate (VI)? Options:
  A) 3
  B) 4
  C) 1
  D) 2
  Show Answer
  The correct answer is D .
• Question 774: The catalyst used in the contact process for the manufacture of tetraoxosulphate (VI) acid is Options:
  A) manganes (IV) oxide
  B) manganese (ll) tetraoxosulphate (VI)
  C) vanadium (V) oxide
  D) iron metal
  Show Answer
  The correct answer is C .
• Question 775: When steam is passed through red hot carbon, which of the following are produced? Options:
  A) Hydrogen oxygen and carbon (IV) oxide
  B) Hydrogen and carbon (IV) oxide
  C) Hydrogen and carbon (II) oxide
  D) Hydrogen and trioxocarbonate (IV) acid
  Show Answer
  The correct answer is C .
• Question 776: Consecutive members of an alkane homologous serires differ by Options:
  A) CH
  B) CH₂
  C) CH₃
  D) C_nH_n
  E) C_nH
  Show Answer
  The correct answer is B .
• Question 777:

  

  From the above diagram, the caustic soda in the conical flask serves to

  Options:
  A) dry ethene gas
  B) remove carbon (iv) oxides from ethene
  C) remove carbon (ii) oxide from ethene
  D) remove sulphur (iv) oxide from ethene
  Show Answer
  The correct answer is C .
• Question 778: An example of a hygroscopic substance is Options:
  A) CuO _(S).
  B) MgCL_2(S).
  C) CaCL_2(S).
  D) NaOH_(S).
  Show Answer
  The correct answer is A .
• Question 779: 20 cm ³ of hydrogen gas are sparked with 20cm ³ of oxygen gas in an endimoeter at 373k (100 ^oC) and 1 atmosphere. The resulting mixture is cooled to 298 K (25 ^oC) and passed over calcium chloride. The volume of the residual gas is Options:
  A) 40 cm ³
  B) 20 cm ³
  C) 30 cm ³
  D) 10cm ³
  E) 5cm ³
  Show Answer
  The correct answer is D .
• Question 780: In the reaction E+F ↔ G+H, the backward reaction is favoured if the concentration of Options:
  A) F is increased
  B) E is increased
  C) E is reduced
  D) G is reduced
  Show Answer
  The correct answer is C .