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 741: If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso₂ and Rch₄ will be in the ratio? (S = 32, O = 16, C = 12, H = 1) Options:
  A) 4:1
  B) 2:1
  C) 1:2
  D) 1:4
  Show Answer
  The correct answer is C .
• Question 742:

  If 30cm³ of oxygen diffuses through a porous pot in 7 seconds, how long will it take 60cm³ of chlorine to diffuse through the same pot, if the vapour densities of oxygen and chlorine are 16 and 36 respectively?

  Options:
  A) 9.3 sec
  B) 14 sec
  C) 21 sec
  D) 28 sec
  E) 30.3 sec
  Show Answer
  The correct answer is C .
• Question 743: Brass and bronze are both metallic alloys. Which of the following constituents is common to both alloys? Options:
  A) Tin
  B) Zinc
  C) Copper
  D) Lead
  E) Aluminium
  Show Answer
  The correct answer is C .
• Question 744:

  How many neutrons are present in atom with mass number and atomic number 37 and 17 respectively?

  Options:
  A) 18
  B) 20
  C) 37
  D) 17
  Show Answer
  The correct answer is B .
• Question 745: Bronze is preferred to copper in the making of medals because it Options:
  A) is stronger
  B) can withstand low temperature
  C) is lighter
  D) has low tensile strength
  Show Answer
  The correct answer is A .
• Question 746: Alkanols have the general molecular formula Options:
  A) C₁H_2n-2
  B) C₁H_2n-1CHO
  C) C₁H_2n-2OH
  D) C₂H_2n+1OH
  Show Answer
  The correct answer is D .
• Question 747:

  3H${}_{2(g)}$+ N2 ⇔ 2NH${}_{3(g)}$ ; H= -ve

  In the reaction above, lowering of temperature will

  Options:
  A) have no effect on the equilibrium position
  B) increase the rate of both the forward and reverse reactions equally
  C) favour the forward reaction
  D) favour the reverse reaction
  Show Answer
  The correct answer is C .
• Question 748: The hybridization of the carbon atom in ethyne is Options:
  A) sp ⁴
  B) sp ³
  C) sp²
  D) sp
  E) s
  Show Answer
  The correct answer is D .
• Question 749: When a salt loses its water of crystallization to the atmosphere on exposure, the process is said to be Options:
  A) Efflorescence
  B) Deliquescence
  C) Effervescence
  D) Fluorescence
  Show Answer
  The correct answer is A .
• Question 750: How many moles of oxygen molecules would be produced from the decomposition of 2.50 moles of potassium trioxochlorate (V)? Options:
  A) 2.50
  B) 3.50
  C) 3.75
  D) 7.50
  Show Answer
  The correct answer is C .