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 1451: When iron is exposed to moist air, it gradually rusts. This is due to the formation of Options:
  A) hydrate iron (III) oxide
  B) anhydrous iron (III) oxide
  C) anhydrous iron (II) oxide
  D) hydrate iron (II) oxide
  Show Answer
  The correct answer is A .
• Question 1452:

  

  Use the graph above to answer this question.

  A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR. The section PQ indicates that X is

  Options:
  A) a mixture of salts
  B) a hydrated salt
  C) an ionic salt
  D) a pure compound
  Show Answer
  The correct answer is D .
• Question 1453: How many electrons are in the L shell of ³¹₁₅P? Options:
  A) 5
  B) 8
  C) 18
  D) 2
  Show Answer
  The correct answer is B .
• Question 1454: The electronic configuration of Mg ²⁺ is Options:
  A) ls ²2s ²2P ⁶3s²3P²
  B) Is²2s²2P⁶
  C) ls²2s²2p⁶3s²
  D) ls²2s²2P⁴
  Show Answer
  The correct answer is B .
• Question 1455: If atom X with six electrons in its outermost shell combines with atom Y with one electron in its outermost shell to form an ionic compound, then? Options:
  A) six atoms of X will combine with one of Y
  B) two atoms of X will combine with six of Y
  C) one atom of X will combine with two of Y
  D) two atoms of X will combine with one of Y
  E) one atom of X will combine with six of Y
  Show Answer
  The correct answer is C .
• Question 1456:

  When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

  Options:
  A) electrovalent bond
  B) co-ordinate bond
  C) ionic bond
  D) covalent bond
  Show Answer
  The correct answer is B .
• Question 1457: Vulcanization involves the removal of Options:
  A) A monomer
  B) The single bond
  C) The double bond
  D) A polymer
  Show Answer
  The correct answer is C .
• Question 1458: What volume of CO₂ at s.t.p would be obtained by reacting trioxocarbonate (IV) with excess acid?(G.M.V at s.t.p = 22.4 dm³) Options:
  A) 2.240 cm ³
  B) 22.40 cm ³
  C) 224.0 cm ³
  D) 2240 cm ³
  Show Answer
  The correct answer is B .
• Question 1459: Methane is member of the homologous series called? Options:
  A) alkenes
  B) alcohols
  C) esters
  D) alkanes
  E) alkynes
  Show Answer
  The correct answer is D .
• Question 1460: In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because Options:
  A) it makes bauxite a better conductor of electricity
  B) it makes bauxite melt at a lower temperature
  C) it makes aluminium purer
  D) it prevents aluminium from getting oxidized
  E) it protects the carbon electrodes used in the process
  Show Answer
  The correct answer is B .