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 291: Magnesium ribbon was added to each of the following aqueous solution in turn: H₂SO₄, AgNO₃, HNO₃, HCl, NH₃, HCl, NH₃. In which case does the magnesium become covered with a dark precipitate? Options:
  A) H₂SO₄
  B) AgNO₃
  C) HNO₃
  D) NH₃
  E) HCl
  Show Answer
  The correct answer is B .
• Question 292: A suitable reagent for distinguish between ethanoic and ethanol is Options:
  A) bromine water
  B) Fehling’s solution
  C) sodium hydrogen trioxocarbonate (iv)
  D) Ammoniacal silver trioxonitrate(V)
  Show Answer
  The correct answer is C .
• Question 293: A red precipitate of copper (I) carbide is formed when ammonium solution of copper (I) chloride is introduced into Options:
  A) CH₂ = CH - CH₂ - CH₃
  B) CH₃ CH₂ - C ≡ CH
  C) CH₃ CH₂ CH₂ CH₃
  D) CH₃ - C C - CH₃
  Show Answer
  The correct answer is B .
• Question 294: An efflorescent compound is a substance that? Options:
  A) absorbs water froom the air without dissolving in it
  B) is capable of giving off coloured luminosity
  C) gives out water to the atmosphere
  D) absorbs water from the air and dissolves in it
  E) gives out its water of crystallization on heating
  Show Answer
  The correct answer is C .
• Question 295:

  What is the molecular geometry of a molecule with three bonding pairs and no lone pairs around the central atom?

  Options:
  A) Tetrahedral
  B) Trigonal planar
  C) Linear
  D) Octahedral
  Show Answer
  The correct answer is B .
• Question 296: A consequence of global warming is Options:
  A) air pollution
  B) water pollution
  C) increased humudity
  D) flooding
  Show Answer
  The correct answer is D .
• Question 297: The acid used in electrolysis of water is dilute Options:
  A) HNO₃
  B) CH₃COOH
  C) H₂SO₄
  D) HCl
  Show Answer
  The correct answer is C .
• Question 298: All these are electromagnetic waves except Options:
  A) White light
  B) Photon
  C) X-ray
  D) Infrared
  Show Answer
  The correct answer is B .
• Question 299: In the process of silver-plating a metal M, the metal M is the? Options:
  A) anode and a driect current is used
  B) cathode and an alternating current is used
  C) anode and an alternating current is used
  D) cathode and a direct current is used
  Show Answer
  The correct answer is B .
• Question 300: The electronic configuration of Mg ²⁺ is Options:
  A) ls ²2s ²2P ⁶3s²3P²
  B) Is²2s²2P⁶
  C) ls²2s²2p⁶3s²
  D) ls²2s²2P⁴
  Show Answer
  The correct answer is B .