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 281: Alkanals can be distinguished from alkanones by the reaction with Options:
  A) sudan lll stain
  B) starch iodide paper
  C) lithium tetrahydrido aluminate (lll)
  D) fehling's solution
  Show Answer
  The correct answer is D .
• Question 282: Which of these properties gives a solid its definite shape? Options:
  A) strong intermolecular attraction
  B) high melting point
  C) high boiling point
  D) weak intermolecular attraction
  Show Answer
  The correct answer is A .
• Question 283: What are the values of x, y and z respectively in the equation: xCu + yHNO₃ → xCu(NO₃)₂ + 4H₂O + zNO? Options:
  A) 4: 1: 2
  B) 3:8:2
  C) 2:8:3
  D) 8:3:2
  Show Answer
  The correct answer is B .
• Question 284: 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 285: Which of the following statements is true? When the potassium atom forms its ion Options:
  A) it gains one electron and becomes neutral
  B) its atomic number decreases
  C) it achieves electronic configuration of orgon
  D) it loses one proton
  E) it loses one neutron
  Show Answer
  The correct answer is C .
• Question 286: The densities of two gases, X and Y are 0.5gdm^-3 and 2.0gdm^-3 respectively. What is the rate of diffusion of X relative to Y? Options:
  A) 0.1
  B) 0.5
  C) 2.0
  D) 4.0
  Show Answer
  The correct answer is C .
• Question 287:

  When the end alkyl groups of ethyl ethanoate are interchanged, the compound formed is

  Options:
  A) propylmethanoate
  B) ethylpropanoate
  C) methyl ethanoate
  D) methyl propanoate
  Show Answer
  The correct answer is B .
• Question 288:

  2-methylprop-1-ene is an isomer of

  Options:
  A) 3-methyl but-1-ene
  B) 2-methyl but-1-ene
  C) but-2-ene
  D) pent-2-ene
  Show Answer
  The correct answer is C .
• Question 289: The structural component that makes detergent dissolve more quickly in water than soap is Options:
  A) -SO₃- Na⁺
  B) -COO-Na^-
  C) -SO₄- Na⁺
  D) -COO-K⁺
  Show Answer
  The correct answer is A .
• Question 290:

  Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas? 

  Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is B .