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 941: 200 cm³ of a gas at 25^oC exerts a pressure of 700 mmHg. Calculate its pressure if its volume increase 350 cm³ at 75^oC. Options:
  A) 342.53 mmHg
  B) 1430.54 mmHg
  C) 467.11 mmHg
  D) 400.00 mmHg
  Show Answer
  The correct answer is C .
• Question 942:

  The velocity, V of a gas is related to its mass, M by (k = proportionality constant)

  Options:
  A) V = $\frac{k}{M}$
  B) V = $\frac{k}{M^{\frac{1}{2}}}$
  C) V = $k{M}^2$
  D) V = $(\frac{k}{M}{)}^{\frac{1}{2}}$
  Show Answer
  The correct answer is B .
• Question 943: When ethene gas reacts with chlorine gas to form 1, 2-dichloroethene, the reaction is called? Options:
  A) substitution
  B) addition
  C) polymerization
  D) hydrolysis
  E) reduction
  Show Answer
  The correct answer is B .
• Question 944: NH_3(g) + HCl_(s) → NH ₄Cl _(s)The entropy change in the system above is Options:
  A) positive
  B) zero
  C) negative
  D) intermediate
  Show Answer
  The correct answer is C .
• Question 945: 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 .
• Question 946:

  A solution contains 20g of solute in 180g of solvent. If the solvent is water, what is the concentration of the solution in terms of mass by mass percentage

  Options:
  A) 11.%
  B) 22.2%
  C) 10%
  D) 20%
  Show Answer
  The correct answer is C .
• Question 947: Cast iron is used in making Options:
  A) Chains and agricultural implements
  B) Iron sheets and retort stand
  C) Nails and iron rods
  D) Stoves and cookers
  Show Answer
  The correct answer is D .
• Question 948: The air around smelting industries is likely to contain Options:
  A) H₂S, CO and N₂
  B) CO₂, SO₃ and H₂
  C) H₂, SO₂ and CO₂
  D) SO₂, N₂ and CO₂
  Show Answer
  The correct answer is C .
• Question 949: Solutions X, Y, and Z have PH values 3.0. 5. 0 and 9. 0 respectively. Which of the following statements is correct? Options:
  A) All the solutions are acidic
  B) All the solutions are basic
  C) Y and Z are more acidic than water
  D) Y is more acidic than X
  E) Z is the least acidic
  Show Answer
  The correct answer is E .
• Question 950: The Avogadro number of 24g of magnesium is the same as that of Options:
  A) 1g of hydrogen molecules
  B) 16g of oxygen molecules
  C) 32g of oxygen molecules
  D) 35.5g of chlorine molecules
  Show Answer
  The correct answer is C .