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 51: If 24.83 cm³ of 0.15 M NaOH is titrated to its end point with 39.45 cm³ of HCl, what is the molarity of the HCl? Options:
  A) 0.094 M
  B) 0.150 M
  C) 0.940 M
  D) 1.500 M
  Show Answer
  The correct answer is A .
• Question 52: The alkyl group can be represented by the general formula Options:
  A) C_nH_2n+1
  B) C_nH_2n
  C) C_nH_2n+2
  D) C_nH_2n-2
  Show Answer
  The correct answer is A .
• Question 53:

  What current in amperes will deposit 2.7g of aluminium in 2 hours?

  [Al = 27, F = 96 500 C mol^-1]

  Options:
  A) 32
  B) 8
  C) 4
  D) 16
  Show Answer
  The correct answer is C .
• Question 54: When a pressure cooker is half filled with water, and heated to boiling point, then the pressure inside the cooker will? Options:
  A) decrease, since only a fraction of the water molecules has changed to vapour
  B) remain constant, because the total number of water molecules has not changed
  C) increase, because the water molecules can now reach every part of the sealed tube
  D) decrease, since water boils under reduced pressure
  E) increase, because the water vapour molecules now strike the walls of the tube more frequently because of their increased velocity
  Show Answer
  The correct answer is E .
• Question 55: When sodium hydroxide is heated with ammonium tetraoxosulphate (IV), the gas given off may be collected by? Options:
  A) bubbling it through concentrated H₂SO₂
  B) bubbling it through water and then passing it through calcium oxide
  C) passing it directly through calcium oxide
  D) passing it directly through calcium chloride
  Show Answer
  The correct answer is C .
• Question 56: Which of the following is arranged in order of increasing electronegativity? Options:
  A) Chlorine, aluminium, magnesium, phosphorus, sodium
  B) sodium, magnesium, aluminium, phosphorus, chlorine
  C) Chlorine, phosphorus, phosphorous, aluminium, magnesium, sodium
  D) Sodium, chlorine, phosphorus, magnesium, aluminium
  Show Answer
  The correct answer is B .
• Question 57: In which of the following is the entropy change positive? Options:
  A) H₂O_(I) → H₂O_(g)
  B) Cu²⁺_{(aq) + Fe(s)} → Fe⁽²⁺⁾ + Cu_(s)
  C) N_2(g) + 3H_2(g) → 2NH_3(g)
  D) 2HCI_(s) → H_2(g) + CI_2(g)
  Show Answer
  The correct answer is A .
• Question 58: Iron is often galvanized in order to Options:
  A) make it more malleable
  B) remove the impurities in it
  C) protect it against corrosion
  D) render it passive
  Show Answer
  The correct answer is C .
• Question 59: (1 /(2) N_2(g) + (1) / (2)O_2(g) → NO_(g) ∆H° 89 KJ mol^-. If the entropy change for the reaction above at 25°C is 11.8 J mol^-, calculate the change in free energy. ∆G°, for the reaction at 25°C? Options:
  A) 88.71 KJ
  B) 85.48 KJ
  C) -204.00 KJ
  D) -3427.40 KJ
  Show Answer
  The correct answer is D .
• Question 60: Which of the following statements is correct about the average kinetic energy of the molecules of a gas? Options:
  A) It increase with increase in pressure
  B) It increase at constant temperature
  C) It increase with increase in temperature
  D) It increase with increase in volume
  Show Answer
  The correct answer is C .