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 1:

  

  The above orbital diagram shown the electronic configuration of

  Options:
  A) chlorine
  B) nitrogen
  C) calcium
  D) neon
  Show Answer
  The correct answer is B .
• Question 2: In which order are the following salts sensitive to light? Options:
  A) Agl > AgCl > AgBr
  B) AgCl > Agl > AgBr
  C) AgBr > AgCl > Agl
  D) AgCl > AgBr > Agl
  Show Answer
  The correct answer is D .
• Question 3: Methane is member of the homologous series called? Options:
  A) alkenes
  B) alcohols
  C) esters
  D) alkanes
  E) alkynes
  Show Answer
  The correct answer is D .
• Question 4:

  

  Choose the correct answer from the options above.

  When Fehling's solution is added to two isomeric carbonyl compounds X and Y with the molecular formula C ₅H ₁₀O, compound X gives a red precipitate while Y does not react. It can be inferred that X is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 5: The air pollutant unknown in nature is Options:
  A) NO
  B) CO
  C) HCHO
  D) DDT
  Show Answer
  The correct answer is C .
• Question 6: Ethanol reacts with excess acidified K₂Cr₂O to produce Options:
  A) ethanedioic acid
  B) ethanal
  C) ethylethanoate
  D) ethanoic acid
  Show Answer
  The correct answer is D .
• Question 7:

  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.

  Compound W is

  Options:
  A) a soap
  B) an oil
  C) an alkane
  D) an ester
  E) sucrose
  Show Answer
  The correct answer is D .
• Question 8: The principle of column chromatography is based on th ability of the constituents to Options:
  A) React with the solvent in the column
  B) React with each other in the solvent in the column
  C) Dissolve in each other in the column
  D) Move at different speeds in the column
  Show Answer
  The correct answer is D .
• Question 9:

  How many moles of limestone will be required to produce 5.6g of CaO?

  [Ca = 40, C = 12, O= 16]

  Options:
  A) 0.20 mol
  B) 0.10 mol
  C) 1.12 mol
  D) 0.56 mol
  Show Answer
  The correct answer is B .
• Question 10:

  PCl_5(g) ↔ PCl_3(g) + Cl_2(g)

  In the reaction above, a decrease in pressure will

  Options:
  A) Decelerate the reaction
  B) Increase the yield of PCl₃
  C) Increase the yield of PCl₅
  D) Accelerate the reaction
  Show Answer
  The correct answer is B .