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 611: At the same temperature and pressure, 50 cm³ of nitrogen gas contains the same number of molecules as? Options:
  A) 25 cm³ of methane
  B) 40 cm³ of hydrogen
  C) 50 cm³ of ammonia
  D) 100 cm³ of chlorine
  Show Answer
  The correct answer is C .
• Question 612:

  If one mole of aluminium contains 6 x 10²³ atoms of aluminium, how many atoms are contained in 0.9g of aluminium?

  (Al = 27)

  Options:
  A) 1.0 x 10²¹
  B) 6.6 x 10²¹
  C) 2.0 x 10²²
  D) 1.0 x 10²²
  E) 5.4 x 10²³
  Show Answer
  The correct answer is C .
• Question 613: Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature? Options:
  A) X and Z
  B) Y
  C) X
  D) Z
  Show Answer
  The correct answer is B .
• Question 614:

  Diamond is a bad conductor of electricity because its bonding electrons are used in

  Options:
  A) crystal lattice formation
  B) covalent bond formation
  C) metallic bond formation
  D) coordinate bond formation
  Show Answer
  The correct answer is B .
• Question 615:

  What is the product of the electrolysis of aqueous sodium chloride (NaCl) using inert electrodes?

  Options:
  A) Hydrogen gas at the cathode and chlorine gas at the anode
  B) Hydrogen gas at the cathode and oxygen gas at the anode
  C) Sodium metal at the cathode and chlorine gas at the anode
  D) Sodium metal at the cathode and oxygen gas at the anode
  Show Answer
  The correct answer is A .
• Question 616:

  The knowledge of half-life can be used to

  Options:
  A) Create an element
  B) Detect an element
  C) Split an element
  D) Irradiate an element
  Show Answer
  The correct answer is C .
• Question 617: In the preparation of some pure crystals of Cu (NO₃)₂ starting with CuO, a student gave the following statements as steps he employed. Which of these shows a flaw in his report ? Options:
  A) some CuO was reacted with excess dilute H₂SO₄
  B) the solution was concentrated
  C) when the concentrate was cooled, crystals formed were removed by filtration
  D) the crystals were washed with very little cold water
  E) the crystals were then allowed to dry
  Show Answer
  The correct answer is A .
• Question 618: A mixture of petrol and water can be separated through Options:
  A) centrifugation
  B) distillation
  C) the use of separating funnel
  D) the use of filter paper
  Show Answer
  The correct answer is C .
• Question 619: A white solid suspected to be lead trioxonitrate (V) zinc trioxocarbonate (IV) or calcium trioxocabonate (IV) was heated strongly. Its residue which was yellow when hot and white when cold is? Options:
  A) lead (II) oxide
  B) calcium oxide
  C) zinc oxide
  D) lead nitrate
  Show Answer
  The correct answer is C .
• Question 620:

  

  The diagram above (Fig.3) shows the energy profile for the reaction A + B + = C + D From this diagram, it is clear that the reaction is

  Options:
  A) spontaneous
  B) isothermal
  C) adiabatic
  D) exothermic
  E) endothermic
  Show Answer
  The correct answer is D .