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 901: Under high pressure, real gases do not obey gas laws because their molecules? Options:
  A) have become more energetic
  B) have become less energetic
  C) have become smaller in size
  D) decompose into atoms
  E) start repelling each other
  Show Answer
  The correct answer is B .
• Question 902:

  How many grams of methylacetylene (propyne) CH₃ - C Ξ CH will completely discharge the colour of 8g of bromine?

  (Br = 80, C = 12, H = 1)

  Options:
  A) 0.5
  B) 1.0
  C) 2.0
  D) 3.0
  E) 4.0
  Show Answer
  The correct answer is B .
• Question 903:

  CO_(g) + H₂ O_(g) → CO_2(g) + H_2(g)

  Calculate the standard heat change of the reaction above, if the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) and CO_(g) in KJ mol ^-1 are - 394 -242 and - 110 respectively.

  Options:
  A) + 262 KJ mol ^-1
  B) - 262 KJ mol ^-1
  C) + 42 KJ mol ^-1
  D) - 42 KJ mol ^-1
  Show Answer
  The correct answer is D .
• Question 904: The reaction Mg + H₂O → MgO + H₂ takes place only in the presence of? Options:
  A) excess Mg ribbon
  B) excess cold water
  C) very hot water
  D) steam
  Show Answer
  The correct answer is D .
• Question 905:

  An unknown organic compound X has a relative molecular mass of 180. It is a colourless crystaline solid, readily soluble in water. X contains the elements C, H and O in the atomic ratio 1: 2:1. The compound has a sweet teste and melts on heating. In the presence of yeast and in the absence of air, X is converted to compound Y and a colourless gas. Compound Y reacts with sodium metal to produce a gas Z which gives a 'pop' sound with a glowing splint. Y also reacts with ethanoic acid to give a sweet smelling compound W.

  Reaction of X with yeast forms the basis of the

  Options:
  A) plastic industry
  B) textile industry
  C) brewing industry
  D) soap industry
  E) dyeing industry
  Show Answer
  The correct answer is C .
• Question 906:

  2-methylprop-1-ene is an isomer of

  Options:
  A) 3-methyl but-1-ene
  B) 2-methyl but-1-ene
  C) but-2-ene
  D) pent-2-ene
  Show Answer
  The correct answer is C .
• Question 907:

  What is the atomic number of aluminium?

  Options:
  A) 13
  B) 26
  C) 14
  D) 12
  Show Answer
  The correct answer is A .
• Question 908: The air pollutant unknown in nature is Options:
  A) NO
  B) CO
  C) HCHO
  D) DDT
  Show Answer
  The correct answer is D .
• Question 909:

  A synthetic rubber is obtained from the polymerization of

  Options:
  A) neoprene
  B) isoprene
  C) butandiene
  D) propylene
  Show Answer
  The correct answer is B .
• Question 910:

  

  From the diagram above, an ideal can be represented by

  Options:
  A) M
  B) N
  C) K
  D) L
  Show Answer
  The correct answer is B .