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 711: In a flame test for calcium, the flame appears Options:
  A) green when viewed through a blue glass
  B) blue when viewed through a blue glass
  C) orange -red when viewed through a blue glass
  D) brick-red when viewed through a blue-glass
  Show Answer
  The correct answer is D .
• Question 712: An eruption pollution an environment with gas suspected to be H₂S, a poisonous gas. A residue team should spray the environment with? Options:
  A) water
  B) moist SO₂
  C) acidified KMnO₄ and water
  D) water, acidified KMnO₄ and oxygen
  Show Answer
  The correct answer is B .
• Question 713:

  CO_(g) + H₂ O_(g) → CO_2(g) + H_2(g)

  Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) and CO_(g) in KJ mol ^-1 are - 394 -242 and - 110 respectively.

  Options:
  A) + 262 KJ mol ^-1
  B) - 262 KJ mol ^-1
  C) + 42 KJ mol ^-1
  D) - 42 KJ mol ^-1
  Show Answer
  The correct answer is D .
• Question 714: Which of the following statement is true of the electrochemical series? Options:
  A) Electropositivity of metals increase down the series
  B) Electropositivity of non-metals decrease down the series
  C) Electronegativity of non-metals decrease down the series
  D) Electropositivity of metals decreases down the series
  Show Answer
  The correct answer is D .
• Question 715:

  A few drop of conc HCL are added to about 10cm${}^3$ of a solution of PH 3.4. The PH of the resulting mixture is?

  Options:
  A) less than 3.4
  B) greater than 3.4
  C) unaltered
  D) the same as that of the pure water
  Show Answer
  The correct answer is A .
• Question 716: Crude copper can be purified by the electrolysis of CuSO_4(aq) if? Options:
  A) platinum electrodes are used
  B) the crude copper is made the anode of the cell
  C) the crude copper is made the cathode of the cell
  D) crude copper electrodes are used
  Show Answer
  The correct answer is B .
• Question 717: What volume of carbon (ll) oxide is produced by reacting excess carbon with 10 dm³ of oxygen? Options:
  A) 5 dm ³
  B) 20 dm ³
  C) 15 dm ³
  D) 10 dm ³
  Show Answer
  The correct answer is B .
• Question 718: The solubility curve shows the variation of solute concentration with Options:
  A) volume
  B) temperature
  C) vapour density
  D) pressure
  Show Answer
  The correct answer is B .
• Question 719: C₃H_8(g) + 50_2(g) → 4H₂O + 3CO_2(g). Form the equation above the volume of oxygen at s.t.p. required to burn 50cm³ of propane is? Options:
  A) 250 cm³
  B) 150 cm³
  C) 100 cm ³
  D) 50 cm³
  Show Answer
  The correct answer is A .
• Question 720: Which of the following conduct electricity? Options:
  A) sulfur
  B) graphite
  C) diamond
  D) red phosphorus
  E) yellow phosphorus
  Show Answer
  The correct answer is B .