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 631: The oxidation of ammonia in excess air produces Options:
  A) NO
  B) N₂O
  C) NO₂
  D) N₂O₄
  Show Answer
  The correct answer is A .
• Question 632: A little quantity of trichloromethane (b.pt 60,^oC) was added to a large quantity of ethanol (b.pt 78,^oC). The most probable boiling point of the resultant mixture is from Options:
  A) 69 ^oC - 70 ^oC
  B) 70 ^oC – 74 ^oC
  C) 82 ^oC – 84 ^oC
  D) 60 ^oC – 78 ^oC
  Show Answer
  The correct answer is C .
• Question 633: Given that electronegativity increases across a period and decreases down a group in the periodic table, in which of the following compounds will the molecules be held together by the strongest hydrogen bond? Options:
  A) HF_(g)
  B) NH_3(g)
  C) CH_4(g)
  D) HCl_(g)
  Show Answer
  The correct answer is A .
• Question 634: Chlorine, bromine and iodine resemble one another in that they Options:
  A) dissolve in alkalis
  B) react violently with hydorgen without heating
  C) are liquids
  D) displace one another from solutiions of their salts
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  The correct answer is D .
• Question 635:

  

  In the diagram above, the curve that represents the production of oxgyen gas from the decomposition of KCIO₃ in the presence of MnO₂ catalyst is

  Options:
  A) R
  B) P
  C) S
  D) Q
  Show Answer
  The correct answer is B .
• Question 636:

  What is the molar mass of water (H2O)?

  Options:
  A) 18 g/mol
  B) 22 g/mol
  C) 16 g/mol
  D) 12 g/mol
  Show Answer
  The correct answer is A .
• Question 637:

  What are the possible oxidation numbers of an element if its atomic number is 17?

  Options:
  A) -1 and 7
  B) -1 and 6
  C) -3 and 5
  D) -2 and 6
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  The correct answer is A .
• Question 638: A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y. Options:
  A) 128
  B) 8
  C) 16
  D) 64
  Show Answer
  The correct answer is A .
• Question 639:

  The compounds made up of only carbon and hydrogen are called?

  Options:
  A) Carbon compounds
  B) Hydrocarbons
  C) Atoms
  D) Carbon hydrolysis
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  The correct answer is B .
• Question 640: Which of the following hydrocarbons is mainly used as fuel? Options:
  A) Methylene
  B) Ethylene
  C) Methane
  D) Ethyne
  Show Answer
  The correct answer is C .