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 181:

  Two cylinders A and B each contains 30 cm³ of

  Oxygen and nitrogen respectively at the same temperature and pressure. If there are 5.0 moles of nitrogen, then the mass of oxygen is?

  Options:
  A) 3.2 g
  B) 6.4 g
  C) 80.0 g
  D) 160.0 g
  Show Answer
  The correct answer is D .
• Question 182: A sample of orange juice is found to have a pH of 3.80. What is he concentration of the hydroxide ion in the juice? Options:
  A) 1.6 x 10^-4
  B) 6.3 x 10^-11
  C) 6.3 x 10^-4
  D) 1.6 x 10^-11
  Show Answer
  The correct answer is B .
• Question 183:

  

  In the diagram above, R is a mixture of

  Options:
  A) potassium tetraxochlorate (VII) and concentrated H₂SO₄
  B) potassium trioxochlorate (V) and concentrated H₂SO₄
  C) potassium tetratoxomanganate (VII) and concentrated HCI
  D) manganes (IV) oxide and concentrated HCI
  Show Answer
  The correct answer is D .
• Question 184: The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains Options:
  A) 78 protons and 55 elections
  B) 55 protons and 78 neutrons
  C) 55 neutrons 78 electrons
  D) 78 protons and 55 neutrons
  Show Answer
  The correct answer is B .
• Question 185:

  

  In the electrolysis of aqueous solution of K₂SO ₄ in the above cell, which species migrate to the anode?

  Options:
  A) SO^2-OH ^-
  B) K ⁺ and SO ₄^2-
  C) OH and HO
  D) H₃O ⁺ and K
  Show Answer
  The correct answer is A .
• Question 186: One mole of a hydrocarbon contains 36g of carbon and its vapour density is 20. The structure of the hydrocarbon is Options:
  A) CH₃C ≡ CH
  B) CH₃CH = CH₂
  C) CH₃CH₂C ≡ CH
  D) CH₃CH₂ CH₃
  Show Answer
  The correct answer is A .
• Question 187: (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 188: In which of the following is the oxidation state of oxygen different from its value in water? Options:
  A) OH^-
  B) H₃O⁺
  C) O^-
  D) H₂O₂
  E) SO₂
  Show Answer
  The correct answer is D .
• Question 189: The oxidation state of oxygen in tetraoxosulphate (VI) acid is Options:
  A) -4
  B) -2
  C) +4
  D) -8
  Show Answer
  The correct answer is B .
• Question 190: Using 50 cm ³ of 1 M potassium hydroxide and 100cm ³ of 1 M tetraoxosulphate (VI) acid, calculate the respective volumes in cm ³ of base and acid that would be required to produce the maximum amount of potassium tetraoxosulphate (IV) [ = 39, S = 32, O = 16, H = 1] Options:
  A) 50, 50
  B) 25, 50
  C) 50, 25
  D) 25, 25
  Show Answer
  The correct answer is D .