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 671:

  What is the mass (in grams) of 500 mL of ethanol? (density of ethanol = 0.789 g/mL)

  Options:
  A) 394.5 mL
  B) 500 mL
  C) 394.5 g
  D) 500 g
  Show Answer
  The correct answer is C .
• Question 672:

  What is the trend for ionization energy across a period in the periodic table?

  Options:
  A) Increases from left to right.
  B) Remains constant
  C) Varies randomly
  D) Decreases from left to right
  Show Answer
  The correct answer is A .
• Question 673:

  A metal M displaces zinc from ZnCl, solution, solution

  This shows that

  Options:
  A) electrons flow from zinc to M
  B) M is more electropositive than zinc
  C) M is more electonegative than zinc
  D) zinc is more electropositive than M
  Show Answer
  The correct answer is B .
• Question 674:

  Which of the following pollutants will lead to the depletion of ozone layer?

  Options:
  A) chlorofluorocarbon
  B) carbon (ii) oxide
  C) hydrogen sulphide
  D) sulphur (iv) oxide
  Show Answer
  The correct answer is A .
• Question 675: Trioxonitrate (V) acid is not used for preparing hydrogen gas from metals because it Options:
  A) is strongly oxidizing
  B) is volatile
  C) renders the metal passive
  D) forms a layer of oxide on the metal
  Show Answer
  The correct answer is A .
• Question 676: Which of the following statements about phosphorus is NOT correct? Options:
  A) Phosphorus is a solid mineral
  B) Phosphorus is obtained by oxidation reaction of phosphate
  C) Phosphorus exists in two allotropic forms
  D) Both forms of phosphorus are interconvertible
  E) Yellow phosporus ignites when rubbed on a rough surface
  Show Answer
  The correct answer is E .
• Question 677:

  Methane is prepared in the laboratory by heating a mixture of sodium ethanoate with soda lime. The chemical constituent(s) of soda lime is/are

  Options:
  A) Ca(OH)${}_2$ and NaOH
  B) Na${}_2$CO${}_3$
  C) NaCl
  D) NaOH
  Show Answer
  The correct answer is A .
• Question 678: The exhaust fumes from a garage in a place that uses petrol of high sulphur content are bound to contain? Options:
  A) CO and SO₃
  B) CO and SO₂
  C) CO,SO₂ and SO₃
  D) CO and H₂S
  Show Answer
  The correct answer is B .
• Question 679: A sample of orange juice is found to have a pH of 3.80. What is he concentration of the hydroxide ion in the juice? Options:
  A) 1.6 x 10^-4
  B) 6.3 x 10^-11
  C) 6.3 x 10^-4
  D) 1.6 x 10^-11
  Show Answer
  The correct answer is B .
• Question 680:

  

  The compound above is the product of the oxidation of

  Options:
  A) 2-methlbutan-2-ol
  B) 2-methylbutan -1- ol
  C) 2, 3-dimethylprop 1-ol
  D) Pentan -2- ol
  Show Answer
  The correct answer is B .