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 1931: A gas that turns a filter paper previously soaked in lead ethanoate solution black is? Options:
  A) hyrogen chloride
  B) hydrogen sulphide
  C) sulphur (IV) oxide
  D) sulphur (VI) oxide
  Show Answer
  The correct answer is B .
• Question 1932: The distance between the nuclei of chlorine atoms in a chlorine molecule is 0.194nm. The atomic radius of chlorine atom is Options:
  A) 0.097nm
  B) 0.914nm
  C) 0.388nm
  D) 2.388nm
  Show Answer
  The correct answer is A .
• Question 1933: Which of the following questions is correct about the periodic table? Options:
  A) The non-metallic properties of the elements tend to decrease across each period
  B) The valence electrons of the elements increase progressively across the period
  C) Elements in the same group have the same numbeer of electron shells
  D) Elements in the same period have the number of valence electrons
  Show Answer
  The correct answer is B .
• Question 1934:

  Which of the following factors does NOT affect the rate of a chemical reaction?

  Options:
  A) Concentration of reactants
  B) Presence of a catalyst
  C) Molecular weight of products
  D) Temperature
  Show Answer
  The correct answer is C .
• Question 1935: When pure aluminium metal is heated to red hot in the presence of nitrogen gas, the compound formed is Options:
  A) Al₂N
  B) Al₂N₂
  C) AlN
  D) Al₂N₃
  Show Answer
  The correct answer is C .
• Question 1936: When excess chlorine is mixed with ethene at room temperature, the product is Options:
  A) 1,2 - dichloroethane
  B) 1,2 - dichloroethene
  C) 1,1 - dichloroethane
  D) 1, 1 - dichloroethene
  Show Answer
  The correct answer is A .
• Question 1937: Which of the following is found in cotton Options:
  A) Starch
  B) Cellulose
  C) Fat
  D) Oil
  Show Answer
  The correct answer is B .
• Question 1938: A hydrocarbon has an empirical formula CH and a vapour density of 39. Determine its molecular formula.[C = 12, H = 1] Options:
  A) C₂H₆
  B) C₃H₈
  C) C₃H₄
  D) C₆H₆
  Show Answer
  The correct answer is D .
• Question 1939:

  The reactions involving simultaneous oxidation and reduction?

  Options:
  A) Automatic reactions
  B) Alternate reactions
  C) Reduction agency
  D) Redox reactions
  Show Answer
  The correct answer is D .
• Question 1940: When air is passed through alkaline pyrogallol and then over quicklime, the only gases left are? Options:
  A) nitrogen and carbondoxide
  B) the rare gases
  C) nitrogen and oxygen
  D) nitrogen and the rare gases
  E) nitrogen, carbonioxide and the rare gases
  Show Answer
  The correct answer is D .