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 2141: When ethanol is heated with excess concentrated sulphuric acid, the ethanol is? Options:
  A) oxidized to ethene
  B) polymerized to polyethene
  C) dehydrated to ethene
  D) dehydrated to ethyne
  Show Answer
  The correct answer is C .
• Question 2142: which of these metals CANNOT replace hydrogen from alkaline solutions? Options:
  A) Aluminium
  B) Zinc
  C) Tin
  D) Iron
  Show Answer
  The correct answer is A .
• Question 2143: An isotope has an atomic number of 17 and a mass number of 36. Which of the following gives the correct number of neutrons and protons in an atom of the isotope? Options:
  A) Neutrons 53, Protons 17
  B) Neutrons 17, Protons 36
  C) Neutrons 19, Protons 17
  D) Neutrons 36, Protons 17
  Show Answer
  The correct answer is C .
• Question 2144: The fraction of crude oil used as jet fuel is Options:
  A) refinery gas
  B) diesel oil
  C) kerosine
  D) gasoline
  Show Answer
  The correct answer is C .
• Question 2145: On heating, which of the following compounds will decompose to the free metal, nitrogen (IV) oxide and oxygen? Options:
  A) Ca(NO₃)₂
  B) Cu(NO₃)₂
  C) AgNO₃
  D) NaNO₃
  Show Answer
  The correct answer is C .
• Question 2146: When a crystal was added to the clear solution of its salt, the crystal did not dissolve and the solution remained unchange. This showed that the solution was Options:
  A) supersaturated
  B) concentrated
  C) unsaturated
  D) saturated
  Show Answer
  The correct answer is D .
• Question 2147: If the elements X and Y have atomic numbers 11 and 17 respectively, what type of bond can they form? Options:
  A) Dative
  B) Covalent
  C) Lonic
  D) Metallic
  Show Answer
  The correct answer is C .
• Question 2148: A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, Find the molecular formula [H = 1, C = 12, O = 16) Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₁₂O₆
  D) C₆H₁₂O₃
  Show Answer
  The correct answer is C .
• Question 2149:

  1.1 g of CaCI₂ dissolved in 50 cm³ of water caused a rise in temperature of3.4°C. The heat of reaction, ∆H for CaCI₂ in kj per mole is?

  (Ca = 40, CI = 35.5, specific heat of water is 4.18 jk^-1

  Options:
  A) -71.1
  B) -4.18
  C) +71.1
  D) +111.0
  Show Answer
  The correct answer is A .
• Question 2150:

  N₂O_4(aq) $\rightleftharpoons$ 2NO_2(g) $△$H = +ve

  In the reaction above, an increase in temperature will

  Options:
  A) Increase the reactant production
  B) Increase the value of the equilibrium constant
  C) Shift the equilibrium to the left
  D) Decrease the value of the equilibrium constant
  Show Answer
  The correct answer is B .