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 1471:

  At 25^o and zymase as catalyst,

  C₆H₁₂₆ → 2C₂H₅OH + 2CO₂ + energy

  The reaction above represented by the equation above is useful in the production of

  Options:
  A) propanol
  B) butanol
  C) methanol
  D) ethanol
  Show Answer
  The correct answer is D .
• Question 1472: Which of the following statements applies during the electroysis of sodium hydroxide sodium hydroxide solution using platinum electrodes? Options:
  A) Na⁺ ions are discharged at the cathode
  B) Hydrogen ions are discharged at the anode
  C) the concentration of sodium hydroxide decrease at both electrode compartments
  D) the concentration of sodium hydroxide increases at the cathode only
  E) the concentration of sodium hydroxide increases at the anode only
  Show Answer
  The correct answer is D .
• Question 1473:

  The combustion of carbon(ii)oxide in oxygen can be represented by equation.

  2CO + O${}_2$ → 2CO${}_2$

  Calculate the volume of the resulting mixture at the end of the reaction if 50cm${}_3$ of carbon(ii)oxide was exploded in 100cm${}_3$ of oxygen

  Options:
  A) 75cm${}^3$
  B) 125cm${}^3$
  C) 100cm${}^3$
  D) 50cm${}^3$
  Show Answer
  The correct answer is B .
• Question 1474: Atomicity of ozone is Options:
  A) 1
  B) 2
  C) 3
  D) 4
  Show Answer
  The correct answer is C .
• Question 1475: Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? Options:
  A) Z is efflorescent
  B) Y and Z are efflorescent
  C) Y and Z are deliquescent
  D) Y and Z are hygroscopic
  E) Y is deliquescent
  Show Answer
  The correct answer is C .
• Question 1476: Ethene reacts with hydrogen bromide to give Options:
  A) CH₂Br₂
  B) CH₃CH₂Br
  C) C₂H₂Br₂
  D) CHBr₂
  Show Answer
  The correct answer is B .
• Question 1477: What happens when the nitrates of potassium, calcium, zinc and copper are separately heated? Options:
  A) All the nitrate will decompose to their respective metals
  B) The nitrates of calcium and potassium will decomposes to their nitrites
  C) Only copper nitrate decomposes to the metal
  D) Only the nitrates of zinc and copper will decompose to their oxides
  E) The nitrates of calcium, zinc and copper decompose to their oxides
  Show Answer
  The correct answer is E .
• Question 1478: Which of the following represents the balanced equation for the reaction of copper with concentrated trioxonitrate (V) acid? Options:
  A) Cu _(s) + 2HNO _3(aq) → Cu (NO ₃) _2(aq) + H _2(g)
  B) Cu _(s) + 4HNO _3(aq) → Cu (NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _2(g)
  C) 3Cu _(s) + 8HNO_3(aq) → 3Cu (NO₃)_2(aq) + 4H₂O₍₁₎ + 2NO_(g)
  D) 3Cu_(s) + 4HNO_3(aq) → 3Cu(NO ₃) _2(aq) + 2H ₂O ₍₁₎ + 2NO _(g)
  Show Answer
  The correct answer is B .
• Question 1479:

  The radio isotope used in industrial radiography for the rapid checking of faults in welds and casting is?

  Options:
  A) carbon-14
  B) phosphorus-32
  C) cobalt
  D) iodine-131
  Show Answer
  The correct answer is C .
• Question 1480: What volume of 0.5 MH₂SO₄ will exactly neutralize 20cm³ of 0.1 MNaOH Solution? Options:
  A) 2.0cm³
  B) 5.0cm³
  C) 6.8cm³
  D) 8.3cm³
  Show Answer
  The correct answer is A .