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 271: An element with atomic number twelve is likely to be Options:
  A) electrovalent with a velocity of 1
  B) electrovalent with a valency of 2
  C) covalent with a valency of 2
  D) covalent with valency of 4
  Show Answer
  The correct answer is B .
• Question 272: 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 273: The process of converting linear alkanes to branched chain and cyclic hydrocarbons by heating in the presence of a catalyst to improve the quality of petrol is referred to as Options:
  A) refining
  B) craching
  C) reforming
  D) blending
  Show Answer
  The correct answer is C .
• Question 274: The chromatography separation of ink is based on the ability of the components to Options:
  A) React with solvent
  B) React with each other
  C) Dissolve in each other in the column
  D) Move at different speeds in the column
  Show Answer
  The correct answer is D .
• Question 275:

  What is the PH of 0.00 1 moldm${}^3$ solution of the sodium hydroxide

  Options:
  A) 14
  B) 13
  C) 12
  D) 11
  Show Answer
  The correct answer is D .
• Question 276: Which of the following ions is acidic? Options:
  A) K⁺
  B) KNO₃^-
  C) S^2-
  D) H₃O⁺
  Show Answer
  The correct answer is B .
• Question 277: In the reaction NH₃ + H⁺ → NH₄⁺, the bond formed results from? Options:
  A) an electron transferred from NH₃ + H⁺
  B) an electron pair donated by NH₃
  C) an electron pair equally shared
  D) an electron pair donated by H⁺
  E) an electron tarnsferred from H⁺ to NH₃
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  The correct answer is B .
• Question 278:

  An example of a polysaccharide is?

  Options:
  A) Dextrose
  B) Mannose
  C) Glucose
  D) Starch
  Show Answer
  The correct answer is D .
• Question 279: The importance of sodium aluminate (III) in the treatment of water is to Options:
  A) cause coagulation
  B) neutralize acidity
  C) prevent goitre and tooth decay
  D) kill germs
  Show Answer
  The correct answer is A .
• Question 280: A few drops of NaOH solution was added to an unknown salt forming a white precipitate which is insoluble in excess solution. The cation likely present is Options:
  A) Zn²⁺
  B) Pb²⁺
  C) Ca²⁺
  D) Al³⁺
  Show Answer
  The correct answer is C .