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 261: A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y. Options:
  A) 128
  B) 8
  C) 16
  D) 64
  Show Answer
  The correct answer is A .
• Question 262: The solvent used for removing grease stain is Options:
  A) turpentine
  B) ammonia solution
  C) ethanol
  D) solution of borax in water
  Show Answer
  The correct answer is B .
• Question 263: A liquid that will dissolve fat is Options:
  A) Hydrochloric acid
  B) Calcium hydroxide
  C) Kerosene
  D) Water
  Show Answer
  The correct answer is B .
• Question 264: 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 265: Brass is an alloy containing copper and? Options:
  A) zinc
  B) tin
  C) aluminium
  D) silver
  E) lead
  Show Answer
  The correct answer is A .
• Question 266: 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 .
• Question 267: Which of the following molecules is held together by hydrogen bond? Options:
  A) CH₄
  B) HBr
  C) H₂SO₄
  D) HF
  Show Answer
  The correct answer is D .
• Question 268: The purest from of iron which contains only about 0.1% carbon is Options:
  A) pig iron
  B) wrough iron
  C) cast iron
  D) iron pyrite
  Show Answer
  The correct answer is B .
• Question 269: Which of the following ions will give a white precipitate with aqueous NaOH and soluble in excess of the base? Options:
  A) Ca²⁺
  B) Mg²⁺
  C) Zn²⁺
  D) Cu²⁺
  Show Answer
  The correct answer is C .
• Question 270: Which of the activities is commonly used as a nuclear fuel Options:
  A) uranium
  B) palladium
  C) actium
  D) thorium
  Show Answer
  The correct answer is A .