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 761:

  Which of the following factors will speed up the rate of evolution of carbon (iv) oxide in the reaction below?

  2HCl + CaCO${}_3$ → CaCl${}_2$ + H${}_2$O + CO${}_2$

  Options:
  A) Increasing the concentration of the acid
  B) Increasing the surface area of CaCO${}_3$
  C) A and B
  D) Reducing the concentration of the acid
  Show Answer
  The correct answer is C .
• Question 762: Which of the following is used as fuel in miners' lamp? Options:
  A) Ethanal
  B) Ethyne
  C) Ethene
  D) Ethane
  Show Answer
  The correct answer is B .
• Question 763: Fermentation is the Options:
  A) breaking down of carbohydrate to glucose
  B) conversion of sugar to alcohol in the presence of yeast
  C) breaking down of sugar to carbohydrate
  D) conversion of alcohol to sugar in the presence of yeast
  Show Answer
  The correct answer is B .
• Question 764: A solution X on mixing with AgNO₃ solution, gives a white precipitate solution in NH₃. A Solution Y, when added to X, also gives a white precipiate which is soluble on boiling. Solution Y contains? Options:
  A) Ag⁺ion
  B) Pb²⁺ion
  C) Pb⁴⁺ion
  D) Zn²⁺ion
  E) Al³⁺ion
  Show Answer
  The correct answer is B .
• Question 765: When a few drops of water is added to a blue anhydrous cobalt (II) chloride, the colour changes to Options:
  A) white
  B) pink
  C) red
  D) blue
  Show Answer
  The correct answer is B .
• Question 766: Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9g of sodium oxalate in 50g of water at room temperature, calculate the minimum volume of 0.1 M calcium oxalate using the above equation? Options:
  A) 1.40 χ 10² dm³
  B) 14.0 χ 10² cm³
  C) 1.40 χ 10^-2 dm^-2
  D) 14.0 χ 10^-2 cm³
  Show Answer
  The correct answer is A .
• Question 767: Argon is used in gas-filled electric lamp because it helps to? Options:
  A) prevent the reduction of the lamp fillaments
  B) prevent oxidation of the lamp fillaments
  C) make the lamp fillament glow brightly
  D) keep the atmosphere in the lamp inert
  Show Answer
  The correct answer is C .
• Question 768: When sodium dioxonitrate (lll) (NaNO₂) dissolves in water, ∆H is positive. The process of dissolution is Options:
  A) exothermic
  B) endothermic
  C) isothermal
  D) isomeric
  E) hygroscopic
  Show Answer
  The correct answer is B .
• Question 769: Which of the following will have its mass increased when heated in air? Options:
  A) Helium
  B) Magnesium
  C) Copper pyrites
  D) Glass
  Show Answer
  The correct answer is B .
• Question 770: When ΔH is negative, a reaction is said to be Options:
  A) endothermic
  B) exothermic
  C) reversible
  D) ionic
  Show Answer
  The correct answer is B .