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 981: The oxide that remains unchanged when heated in hydrogen is? Options:
  A) CuO
  B) Fe₂O₃
  C) PbO₂
  D) ZnO
  Show Answer
  The correct answer is B .
• Question 982: 60cm³ of hydrogen are sparked with 20cm³ of oxygen at 100°C and 1 atmosphere. The total volume of the residual gases is? Options:
  A) 60 cm³
  B) 10 cm³
  C) 40 cm³
  D) 30 cm³
  E) 70 cm³
  Show Answer
  The correct answer is A .
• Question 983: The minimum volume of oxygen required for the complete combustion of a mixture of 10cm ³ of CO and 15 cm ³ of H ² is Options:
  A) 25.0cm³
  B) 12.5 cm³
  C) 10.0 cm³
  D) 5.0cm³
  Show Answer
  The correct answer is C .
• Question 984:

  Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore,

  Options:
  A) P will form an electrovalent bond with R
  B) Q will form a covalent bond with S
  C) R will form an electrovalent bond with S
  D) Q will form an electrovalent bond with S
  Show Answer
  The correct answer is D .
• Question 985: Which of the following metals burn with brick red flame? Options:
  A) Pb
  B) Ca
  C) Na
  D) Mg
  Show Answer
  The correct answer is B .
• Question 986: Two equal bulbs, one containing ammonia and the other one opened mouth-to mouth to each other at temperature the entropy in the mixture of gases is likely to Options:
  A) remain unchanged
  B) increase
  C) decrease
  D) charge
  Show Answer
  The correct answer is A .
• Question 987: Which of the additives could improve the quality of steel? Options:
  A) Silicon
  B) Sulphur and phosphorus
  C) Carbon
  D) Chromium and nickel
  Show Answer
  The correct answer is D .
• Question 988:

  The volume occupied by 1.58g of a gas at S.T.P is 500cm${}^3$. What is the relative molecular mass of the gas?  [ G.M.V at S.T.P = 22.4dm${}^3$ ]

  Options:
  A) 28
  B) 32
  C) 44
  D) 71
  Show Answer
  The correct answer is D .
• Question 989: The major and most effective way of controlling pollution is to Options:
  A) improve machinery so that the substances released from combustion are less harmful
  B) pass strict laws against it by individuals and companies
  C) educate people on the causes and effects of pollution
  D) convert chemical wastes to harmless substances before releasing them into the environment
  Show Answer
  The correct answer is C .
• Question 990: Kerosine is commonly used to remove the red colour stain of palm oil from cloths because it Options:
  A) helps to spread the oil over a larger surface area
  B) react with the oil to form an odourless compound
  C) makes the oil evaporate easily by dissolving it
  D) helps to dilute the oil and reduce its colour
  Show Answer
  The correct answer is C .