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 741: Carbon is tetravalent because Options:
  A) The electrons in both the 2s and 2p orbitals are equivalent
  B) The electrons in all the orbitals of carbon are equivalent
  C) The 2s and 2p atomic orbitals hybridize
  D) All the atomic orbitals of carbon hybridize
  Show Answer
  The correct answer is A .
• Question 742: A cycloalkane with the molecular formula C₅H₁₀ has ? Options:
  A) one isomer
  B) two isomers
  C) three isomers
  D) four isomers
  Show Answer
  The correct answer is C .
• Question 743: A decrease in atomic size and an increase in nuclear charge across a period lead to Options:
  A) an increase in the tendency to lose electron
  B) an increase in chemical reactivity
  C) a decrease in electropositivity
  D) a decrease in covalency in bond formation
  Show Answer
  The correct answer is B .
• Question 744:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100°C, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0°C?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 745: The mixture of gases used in a photographer's flash tube is Options:
  A) argon and krypton
  B) krypton and xenon
  C) helium and argon
  D) argon and xenon
  Show Answer
  The correct answer is B .
• Question 746: A common characteristic between zinc and the other transition elements is the ability to Options:
  A) have variable oxidation states
  B) from complex ions
  C) act as a catalyst
  D) from coloured ions
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  The correct answer is B .
• Question 747: A chemical reaction which the hydration energy is greater than the lattice energy is referred to as Options:
  A) a spontaneous reaction
  B) an endothermic reaction
  C) an exothermic reaction
  D) a reversible reaction
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  The correct answer is C .
• Question 748: What is the pH of 0.001 mol dm4 solution of sodium hydroxide? Options:
  A) 14
  B) 13
  C) 12
  D) 11
  E) 10
  Show Answer
  The correct answer is D .
• Question 749: The Avogadro number of 24g of magnesium is the same as that of Options:
  A) 1g of hydrogen molecules
  B) 16g of oxygen molecules
  C) 32g of oxygen molecules
  D) 35.5g of chlorine molecules
  Show Answer
  The correct answer is C .
• Question 750: In which of the following are water molecules in the most disorderly arrangement? Options:
  A) Ice at -10°C
  B) Ice at 0°C
  C) Water at 100°C
  D) Steam at 100°C
  Show Answer
  The correct answer is D .