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 341: What is the decrease in volume of air when pyrogallol is shaken with 30.00cm³ of air ? Options:
  A) 15.00cm³
  B) 6.30cm³
  C) 0.63cm³
  D) 0.06cm³
  Show Answer
  The correct answer is B .
• Question 342:

  What mass of K₂CrO₄ is required to prepare 250cm³ of 0.020 mol dm³ solution?

  [K₂CrO₄ = 194.2g mol^-1]

  Options:
  A) 0.97g
  B) 9.70g
  C) 19.42g
  D) 97.10g
  Show Answer
  The correct answer is A .
• Question 343:

  Calculate the volume in cm³ of oxygen evolved as s.t.p. when a current of 5 A is passed through acidified water for 193s

  {F = 96500 Cmol^-1, Molar volume of a gas at s.t.p. = 22.4 dm³}

  Options:
  A) 224.000 dm³
  B) 0.056 dm³
  C) 0.224 dm³
  D) 56.000 dm³
  Show Answer
  The correct answer is B .
• Question 344:

  2SO_2(g) + O_2(g) $⟺$2SO_3(g)

  $△H=-395.7kJmo{l}^{-1}$

  In the reaction above, the concentration of 2SO_3(g) can be in creased by

  Options:
  A) decreasing the pressure
  B) decreasing the temperature
  C) the addition of catalyst
  D) increasing the temperature
  Show Answer
  The correct answer is B .
• Question 345:

  Which important nitrogen-containing compound is produced in Haber's process?

  Options:
  A) NH${}_3$
  B) NO${}_2$
  C) NO
  D) HNO${}_3$
  Show Answer
  The correct answer is A .
• Question 346:

  2H${}_2$ + O${}_2$ 2H${}_2$O

  From the equationabove, calculate the volume of unreacted oxygen gas if a mixture of 50cm${}^3$ of hydroden and 75cm${}^3$ of oxygen are involved

  Options:
  A) 85cm${}^3$
  B) 50cm${}^3$
  C) 125cm${}^3$
  D) 55cm${}^3$
  Show Answer
  The correct answer is B .
• Question 347:

  The most abundant rare gas in the atmosphere is?

  Options:
  A) He
  B) Ne
  C) Ar
  D) Xe
  Show Answer
  The correct answer is C .
• Question 348:

  

  The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X_(g) + Y_(g) → XY_(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X_(g) + Y_(g)

  Options:
  A) 300, 500
  B) 500, 300
  C) -300, -500
  D) -500, -300
  Show Answer
  The correct answer is A .
• Question 349:

  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 350: N₂O_4(g)→ 2NO_2(g)In the endothermic reaction above, more products formed will be favored by Options:
  A) A constant values
  B) an increase in pressure
  C) a decrease pressure
  D) a decrease volume
  Show Answer
  The correct answer is C .