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 821:

  10g of a solid is in equilibrium with its own vapour.

  When 1 g of a small amount of solid is added, the vapour pressure?

  Options:
  A) remains the same
  B) drops
  C) increases by 1%
  D) increases by 99%
  Show Answer
  The correct answer is B .
• Question 822: An increase in temperature causes an increase in the pressure of a gas because? Options:
  A) it decreases the number of collision between the molecules
  B) the molecules of the gas bombard the walls of the container more frequently
  C) it increases the number of collision between the molecules
  D) it causes the molecules to combine
  Show Answer
  The correct answer is C .
• Question 823: An endothermic reaction is one during which heat is.....and can be represented by the symbol.... which of the following combinations can be used accurately to complete the above definition? Options:
  A) liberated, -$\mathrm{\Delta }$H
  B) liberated, +$\mathrm{\Delta }$H
  C) absorbed, -$\mathrm{\Delta }$H
  D) absorbed, +$\mathrm{\Delta }$H
  E) absorbed, +$\mathrm{\Delta }$G
  Show Answer
  The correct answer is D .
• Question 824: A few drops of concentrated HNO₃ is added to an unknown solution and boiled for a while. If this produces a brown solution, the cation presents is likely to be Options:
  A) Pb²⁺
  B) Cu²⁺
  C) Fe³⁺
  D) Fe²⁺
  Show Answer
  The correct answer is D .
• Question 825: Which of the following processes takes place during electrolysis? Options:
  A) Positive ions are discharged at the anode bby gaining sufficient electrons to become neutral
  B) Negative ions are dicharged at the anode by gaining suficient electrons to become neutral
  C) Positive ions are discharged at the anode by losing sufficient electrons to become neutral
  D) Negative ions are discharge at the anode by losing sufficient electrons to become neutral
  E) Nothing happens
  Show Answer
  The correct answer is D .
• Question 826:

  N₂O_4(g) ↔ 2NO_2(g) ΔH = +ve

  In the reaction above, an increase in temperature will

  Options:
  A) increase the value of the equilibrium constant
  B) decreases the value of the equilibrium constant
  C) increase in the reactant production
  D) shift the equilibrium to the left
  Show Answer
  The correct answer is A .
• Question 827: A molar solution of caustic soda is prepared by dissolving Options:
  A) 40 g NaOH in 100 g of water
  B) 40 g NaOH in 1000 g of water
  C) 20 g NaOH in 500 of solution
  D) 20 g NaOH in 1000 g of solution
  E) 2o g NaOH in 80 g of solution
  Show Answer
  The correct answer is B .
• Question 828: The most abundant element on the earth's crust is Options:
  A) nitrogen
  B) hydrogen
  C) oxygen
  D) flourine
  Show Answer
  The correct answer is C .
• Question 829: The highest rate of production of carbon (lV) oxide can be achieved using Options:
  A) 0.05 mol ^-3HCI and 5g powdered CaCO₃
  B) 0.05 mol ^-3HCI and 5g lump CaCO₃
  C) 0.10 mol ^-3HCI and 5g powdered CaCO₃
  D) 0.025 mol ^-3HCI and 5g powdered CaCO₃
  Show Answer
  The correct answer is C .
• Question 830: Leads is used for making bullets and lead shots because of its Options:
  A) resistance to corrosion
  B) low melting point
  C) high density
  D) flexibility
  Show Answer
  The correct answer is C .