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 921:

  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 922: For a given solute, the concentration of its saturated solution in different solvents are Options:
  A) the same at the same temperature
  B) different at the same temperature
  C) the same at different temperature
  D) constant
  Show Answer
  The correct answer is B .
• Question 923: Copper metal dissolves in concentrated trioxonitrate (V) acid with the resultant evolution of Options:
  A) CO₂
  B) SO₂
  C) NO₂
  D) CO
  Show Answer
  The correct answer is C .
• Question 924: MnO_4(aq) + 8H + _(aq) + 5Fe²⁺ → Mn^2+(aq) + 4H₂O_(I). The oxidation number of manganese in the above reaction changed from? Options:
  A) +7 to +2
  B) +6 to +2
  C) +5 to +2
  D) +4 to +2
  Show Answer
  The correct answer is A .
• Question 925: When hydrogen sulphide and sulphur dioxide are each passed in turn into a solution of potassium dichromate? Options:
  A) both gases change the colour of the solution from yellow to colourless
  B) both gases causes sulphur to be deposited
  C) only hydrogen sulphide decolourizes the solution
  D) only sulphur dioxide deposits sulphur
  E) only hydrogen sulphide deposits sulphur
  Show Answer
  The correct answer is E .
• Question 926: Which of the following in aqueous solution is neutral to litmus? Options:
  A) NH₄CI
  B) NaCO₃
  C) FeCl₃
  D) NaCl
  Show Answer
  The correct answer is D .
• Question 927: When chlorine is passed into water and subsequently exposed to sunlight, the gas evolved is? Options:
  A) HCl
  B) HOCl
  C) O₂
  D) Cl₂O
  Show Answer
  The correct answer is C .
• Question 928: Which of the following properties is NOT peculiar to matter? Options:
  A) kinetic energy of particles increase from solid to gas
  B) Random motion of particles increases from liquid to gas
  C) Orderliness of particles increases from gas to liquid
  D) Random motion of particles increases from gas to solid
  Show Answer
  The correct answer is D .
• Question 929: Which of the following electrodes is used in electrolysis of bauxite (Al₂O₃) in molten cryolite? Options:
  A) Steel electrodes
  B) Carbon electrodes
  C) Mercury electrodes
  D) Carbon anode and steel cathode
  E) Carbon cathode and stell anode
  Show Answer
  The correct answer is B .
• Question 930: The filter in the cigarette reduces the nicotine content by Options:
  A) Burning
  B) Adsorption
  C) Evaporation
  D) Absorption
  Show Answer
  The correct answer is B .