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 1871:

  

  The above diagram gives the potential energy profile of the catalyst and uncatalysed reactions of X_(g) + Y_(g) → XY_(g). Deduce the respective activation energies in KJ of the catalysed and uncatalysed reverse reactions: XY(g) → X_(g) + Y_(g)

  Options:
  A) 300, 500
  B) 500, 300
  C) -300, -500
  D) -500, -300
  Show Answer
  The correct answer is A .
• Question 1872: Liquid X, reacts with sodium trioxocarbonate (IV) (Na₂CO₃) to give a gas which turns calcium chloride solution milky X is Options:
  A) Na₂SO₄(aq)
  B) Kl (aq)
  C) an alkali
  D) an acid
  E) a hydrocarbon
  Show Answer
  The correct answer is D .
• Question 1873: The experiment that showed that atoms have tiny positively charged nucleus was first carried out by Options:
  A) Moseley
  B) Rutherford
  C) Millikan
  D) Dalton
  Show Answer
  The correct answer is B .
• Question 1874: A major process involved in the softening of hard water is the? Options:
  A) conversation of a soluble calcium salt to its trioxoncarbonate (lV)
  B) decomposition of calcium rioxocarbonate (lV)
  C) conversion of an insoluble calcium salts to its trioxocarbonate (lV)
  D) oxidation of calcium atoms to its ions
  Show Answer
  The correct answer is A .
• Question 1875:

  The scientist who stated that matter can be converted into energy is?

  Options:
  A) Boyle
  B) Lavoiser
  C) Avogadro
  D) Einstein
  Show Answer
  The correct answer is D .
• Question 1876: Fats and oils are? Options:
  A) addition products of long chain fatty acids and alkali
  B) addition products of long-chain fattyy acids and glycerol
  C) condensation products of long-chain fatty acids and glycerol
  D) condensation products of formaldehyde and glycerol
  E) liquids at 20°C
  Show Answer
  The correct answer is C .
• Question 1877: When a solution of ammonium trioxocarbonate (IV) is added to a solution of an unknown salt, a white precipitate which is soluble in dilute hydrochloric acid but insoluble in ethanoic acid is formed. This indicates the presence of Options:
  A) Ca²⁺
  B) Na⁺
  C) Zn²⁺
  D) K⁺
  Show Answer
  The correct answer is A .
• Question 1878: The ores that can be concentrated by flotation are Options:
  A) nitride ores
  B) sulphide ores
  C) oxide ores
  D) non-metals
  Show Answer
  The correct answer is B .
• Question 1879: A blue solid, T, which weighed 5.0g was placed on a table. After 8 hours, the resulting pink solid was found to weigh 5.5g. It can be inferred that substance T? Options:
  A) is deliquescent
  B) is hydroscopic
  C) has some molecules of water of crystallization
  D) is efflorescent
  Show Answer
  The correct answer is A .
• Question 1880: Four elements P,Q,R and S have 1,2,3, and 7 electrons in their outermost shells respectively. The element which is unlikely to be a metal is? Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is D .