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 1721: Which of the following electron configurations indicates an atom with the highest ionization energy? Options:
  A) 2,8,7
  B) 2,8,8,1
  C) 2,8,8,2
  D) 2,8,8,7
  Show Answer
  The correct answer is A .
• Question 1722: Iron is often galvanized in order to Options:
  A) make it more malleable
  B) remove the impurities in it
  C) protect it against corrosion
  D) render it passive
  Show Answer
  The correct answer is C .
• Question 1723: A gas that is not associated with global warming is Options:
  A) CO₂
  B) SO₃
  C) CH₄
  D) H₂
  Show Answer
  The correct answer is A .
• Question 1724: When ammonium, potassium and calcium carbonates are each separately heated Options:
  A) none of them will decompose
  B) each of them will decompose to give carbondioxide and the respective oxide
  C) ammonium carbonate and potassium carbonate will not decompose
  D) only ammonium carbonate and the respective oxide
  E) ammonium carbonate will decompose to give carbondioxide, water and ammonia
  Show Answer
  The correct answer is D .
• Question 1725: What volume of 1.5M solution of KOH would contain 0.045 moles Options:
  A) 67.50 cm³
  B) 30.00 cm³
  C) 6.75 cm³
  D) 3.00 cm³
  Show Answer
  The correct answer is B .
• Question 1726: Oxyacetylene flame is used for iron-welding because it Options:
  A) Makes the iron metals solidify very quickly
  B) Combines with oxygen to give a pop sound
  C) Evolves a lot of heat when burnt
  D) Dissociates to produce carbon (IV) oxide and oxygen
  Show Answer
  The correct answer is C .
• Question 1727:

  Atoms of element X (with 2 electrons in the outer shell). combine with atoms of Y (with 7 electrons in the outer shell).

  Which of the following statements is FALSE? The compound formed

  Options:
  A) has formula XY
  B) is likely to be ionic
  C) contains X²⁺ ions
  D) contains Y^- ions
  Show Answer
  The correct answer is A .
• Question 1728: The synthetic detergents are preferred to soap for laundry using hard water because? Options:
  A) detergents are water soluble while soap is not
  B) the calcium salts of detergents are water soluble
  C) the magnesium salt of soap is soluble in hard water
  D) soap does not have a hydrocarbon terminal chain
  Show Answer
  The correct answer is B .
• Question 1729:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 1730: The pair of metals in the reactivity series that are usually extracted by the electrolysis of their ores is Options:
  A) magnesium and zinc
  B) magnesium and calcium
  C) copper and zinc
  D) lead and calcium
  Show Answer
  The correct answer is B .