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 91: Indicate which of the following statements is not true as we move from left to right along the periodic Table: Options:
  A) atomic number of elements increases
  B) atomic mass of elements increases
  C) electropositive character of elements increases
  D) electronegative character of elements increases
  E) number of electrons in the outermost orbits of element increases
  Show Answer
  The correct answer is C .
• Question 92: The group IA metals are not found free in nature because they Options:
  A) are very reactive and unstable
  B) are malleable and ductile
  C) have high melting and boiling point
  D) conduct heat and electricity
  Show Answer
  The correct answer is A .
• Question 93: The enzyme used in the hydrolysis of starch to dextrin and maltose is Options:
  A) Zymase
  B) Sucrase
  C) Amylase
  D) Lactase
  Show Answer
  The correct answer is C .
• Question 94: Which of the following metals can be prepared in samples by the thermal decomposition of their trioxonitrate (V) salts? Options:
  A) Copper and mercury
  B) Silver and copper
  C) Mercury and silver
  D) Magnesium and mercury
  Show Answer
  The correct answer is C .
• Question 95: Increasing the pressure of a gas Options:
  A) lowers the average kinetic energy of the molecules
  B) decreases the density of the gas
  C) decreases the temperature of the gas
  D) increases the density of the gas
  E) increases the volume of the gas
  Show Answer
  The correct answer is D .
• Question 96: The electron configuration of two elements with similar chemical properties are represented by? Options:
  A) 1s²2s²2p⁵ and 1s²2s²2p⁴
  B) 1s²2s²2p⁴ and 1s²2s²2p⁶3s¹
  C) 1s²2s²2p⁶3s¹ and 1s²2s¹
  D) 1s²2s²2p⁴ and 1s²2s¹
  Show Answer
  The correct answer is C .
• Question 97: The product formed at the the cathode during the electrolysis of sodium chloride solution with carbon electrodes is? Options:
  A) sodium
  B) chlorine
  C) hydrogen
  D) sodium hydroxide
  E) oxygen
  Show Answer
  The correct answer is C .
• Question 98:

  

  Choose the correct answer from the options above.

  When Fehling's solution is added to two isomeric carbonyl compounds X and Y with the molecular formula C ₅H ₁₀O, compound X gives a red precipitate while Y does not react. It can be inferred that X is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 99: Dissolving some pellets of NaOH in water would result in Options:
  A) a decrease in the free energy of the solution
  B) a decrease in the entropy of the solution
  C) a lowering of the temperature of te solution
  D) an increase in the entropy of the solution
  Show Answer
  The correct answer is D .
• Question 100: A constituent common to bronze and solder is Options:
  A) lead
  B) silver
  C) copper
  D) tin
  Show Answer
  The correct answer is D .