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 1001: Phosphorus burns in oxygen according to the equation P₄ + 50₂ → P₄O₁₀. How many litres of oxygen will be required at S.T.P for complete oxidation of 12.4g of phosphorus? [P = 31,O = 16 and molar volume of a gas at S.T.P = 22.4 litres] Options:
  A) 5. 20
  B) 11. 20
  C) 2. 24
  D) 20. 20
  E) 6. 20
  Show Answer
  The correct answer is B .
• Question 1002: The hydrocarbon that burns in air with a sooty flames is Options:
  A) C₂H₆
  B) C₃H₈
  C) C₄H₁₀
  D) C₆H₆
  Show Answer
  The correct answer is D .
• Question 1003:

  

  In the diagram above, curve X represents the energy profile for a homogeneous gaseous reaction. Which of the following conditions would produce curve Y for the same reaction?

  Options:
  A) Increase in temperature
  B) Increase in the concentration of a reactant
  C) Addition of a catalyst
  D) Increase in pressure
  Show Answer
  The correct answer is C .
• Question 1004: The most volatile fraction obtained from fractional distillation of crude petroleum contains? Options:
  A) butane , propane and kerosene
  B) butane , propane and petrol
  C) ethane, methane and benzene
  D) methane, ethane and propane
  Show Answer
  The correct answer is D .
• Question 1005: Which of the following statements is INCORRECT?
  Options:
  A) Fractional distillation of crude petroleum will give the folloing hydrocarbon fuels in order of increasing boiling point
  B) Butane < petrol < kerosene of polythene.
  C) Both but-1-ene and but-1-yne will decolorize bromine readily
  D) but-2-ene will react with chlorine to form 2,3-dichlorobutane
  E) calcuim carbide will react with water to form any alkyne
  Show Answer
  The correct answer is E .
• Question 1006: Which of the following relationships between the pressure P, the volume V and the temperature T, represents an ideal gas behaviour? Options:
  A) P $\alpha$ VT
  B) P $\alpha$ T/V
  C) PT $\alpha$ V
  D) PV $\alpha$ I/T
  E) P $\alpha$ V/T
  Show Answer
  The correct answer is B .
• Question 1007: The reaction between sulphur (IV) oxide and oxygen is represented by the equilibrium reaction 2SO_2(g) + O_2(g) ↔ 2SO_3(g), ∆H = -196 kJ. What factor would influence increased production of SO_3(g)? Options:
  A) Addition of a suitable catalyst
  B) Increase in the temperature of the reaction
  C) Decrease in the temperature of the reaction
  D) Decrease in the concentration of SO_2(g)
  Show Answer
  The correct answer is C .
• Question 1008: 30 cm³ of 0.1 M Al (NO₃)₃ SOLUTION IS RECTED WITH 100cm³ of 0.15M of NaOH solution. Which reactant is in excess, and by now much ? Options:
  A) NaOH solution by 70 cm³
  B) NaOH solution, by 60 cm³
  C) NaOH solution by 40 cm³
  D) Al(NO₃)₃ solution by 20 cm³
  E) Al(NO₃)₃ solution by 10 cm³
  Show Answer
  The correct answer is C .
• Question 1009: The knowledge of half-life can be used to Options:
  A) create an element
  B) detect an element
  C) split an element
  D) irradiate an element
  Show Answer
  The correct answer is A .
• Question 1010:

  H_2(g) + Br_2(g) → 2HBr_(g)

  The above reaction is carried out at 25^oC. ΔH is -72 kJ mol^-1 and ΔS is - 106 J mol^-1K^-1, the reaction will

  Options:
  A) not proceed spontaneously at the given
  B) proceed spontaneously at the given temperature
  C) proceed in the reverse direction at the given temperature
  D) proceed spontenously at lower temperature
  Show Answer
  The correct answer is A .