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 281: Water is said to be temporarily hard when it contains Options:
  A) Ca (HCO₃)₂ and Mg (HCO₃)₂ salts
  B) Ca (HCO₃)₂ and CaCO₃ SALTS
  C) Mg(HCO₃)₂ and CaSO₄ salts
  D) CaSO₄ and Ca(HCO₃)₂ salts
  Show Answer
  The correct answer is A .
• Question 282:

  Which of the following is an example of a primary cell?

  Options:
  A) Alkaline battery
  B) Nickel-cadmium battery
  C) Lead-acid battery
  D) Lithium-ion battery
  Show Answer
  The correct answer is A .
• Question 283: The oxidation state of oxygen on tetraoxosulphate iv acid is Options:
  A) -4
  B) -2
  C) 4
  D) -8
  Show Answer
  The correct answer is B .
• Question 284: 2-methylprop-1-ene is an isomer of Options:
  A) but-2-ene
  B) pent-1-ene
  C) 2-methylbut-2-ene
  D) 2-methylbut-1-ene
  Show Answer
  The correct answer is A .
• Question 285:

  C₂H₅ - C = CH₂

  CH₃The correct name of the compound with the above structural formula is

  Options:
  A) 2-methylbut -1-ene
  B) 2-methylbut -2-ene
  C) 2-methylbutane
  D) 2-ethylprop-1 -ene
  E) 2-ethylprop-2-ene
  Show Answer
  The correct answer is A .
• Question 286:

  How many grams of hydrogen gas will be liberated when 6g of magnesium ribbon dissolves in 500cm³ of 6M HCl?
  (Mg = 24, H = 1, Cl = 35.5)

  Options:
  A) 1.2 g
  B) 0.7 g
  C) 0.5 g
  D) 0.3 g
  E) 0.12 g
  Show Answer
  The correct answer is C .
• Question 287:

  The IUPAC nomenclature of the compound

  H${}_3$C - CH(CH${}_3$) - CH(CH${}_3$) - CH${}_2$ - CH${}_3$

  Options:
  A) 3,4- dimethylhexane
  B) 2,3- dimethyl pentane
  C) 2- ethyl hexane
  D) 2,3- dimethylhexane
  Show Answer
  The correct answer is B .
• Question 288: An isomer of C₅H₁₂ is Options:
  A) 2–ethyl butane
  B) butane
  C) 2–methyl butane
  D) 2–methyl propane
  Show Answer
  The correct answer is C .
• Question 289: If the temperature of a gas is increased? Options:
  A) the kinetic energy of the emolecules will decrease
  B) the pressure will decrease if the volume is constant
  C) the gas will occupy a greater volume if the pressure is constant
  D) the mass of the gas will decrease
  E) the pressure and volume will increase
  Show Answer
  The correct answer is C .
• Question 290:

  The part of the total energy of a system that accounts for the useful work done in a system is known as

  Options:
  A) Enthalpy change
  B) None of the above
  C) Gibb's free energy
  D) Entropy
  Show Answer
  The correct answer is C .