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 1861:

  Which of the following reactions would be expected to have the highest entropy change?

  Options:
  A) Liquid → Gas
  B) Solid → Liquid
  C) Gas → Liquid
  D) Gas → Solid
  Show Answer
  The correct answer is A .
• Question 1862:

  

  In the diagram above , the activation energy for the backward reaction is

  Options:
  A) +5kJ
  B) +15KJ
  C) +25KJ
  D) +30KJ
  Show Answer
  The correct answer is C .
• Question 1863: Smog usually occurs over cities which Options:
  A) burn a lot of fossil fuels
  B) have very few plants
  C) are surrounded by water
  D) are overpopulated
  Show Answer
  The correct answer is A .
• Question 1864:

  A solution X, on mixing with AgNO${}_3$ solution gives a white precipitate soluble in aqueous NH${}_3$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

  Options:
  A) Al${}^{3+}$, Cl${}^{-}$
  B) Hg${}^{+}$, SO${}_4^{2-}$
  C) Pb${}^{2+}$, Cl${}^{-}$
  D) Ag${}^{+}$, SO${}_4^{2-}$
  Show Answer
  The correct answer is C .
• Question 1865: The air around a petroleum refinery is most likely to contain? Options:
  A) CO₂, SO₃ and N₂O
  B) CO₂, CO and N₂O
  C) SO₂, CO and NO₂
  D) PH₃ H₂O and CO₂
  Show Answer
  The correct answer is C .
• Question 1866:

  Which of the following is an example of an endothermic reaction?

  Options:
  A) Combustion of propane (C${}_3$H${}_8$) to produce carbon dioxide (CO${}_2$) and water (H${}_2$O).
  B) Burning of methane (CH${}_4$) in the presence of oxygen
  C) Formation of table salt (NaCl) from sodium (Na) and chlorine (Cl${}_2$).
  D) Decomposition of hydrogen peroxide (H${}_2$O${}_2$) into water (H${}_2$O) and oxygen (O${}_2$).
  Show Answer
  The correct answer is D .
• Question 1867: Water is said to be temporarily hard when it contains Options:
  A) Ca (HCO₃)₂ and Mg (HCO₃)₂ salts
  B) Ca (HCO₃)₂ and CaCO₃ SALTS
  C) Mg(HCO₃)₂ and CaSO₄ salts
  D) CaSO₄ and Ca(HCO₃)₂ salts
  Show Answer
  The correct answer is A .
• Question 1868:

  CH₃ - CH₂ - C CH

  The hybridization in the compound above is

  Options:
  A) Sp²
  B) sp
  C) sp³ and sp²
  D) sp³ and sp
  Show Answer
  The correct answer is D .
• Question 1869: The shape of the S-orbital is Options:
  A) elliptical
  B) spiral
  C) circular
  D) spherical
  Show Answer
  The correct answer is D .
• Question 1870: The products of the thermal decomposition of ammonium trioxonitrate (V) are Options:
  A) NO ₂ and oxygen
  B) NH₃ and oxygen
  C) nitrogen and water
  D) N₂O and water
  Show Answer
  The correct answer is D .