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 121: The salt formed from a weak acid and a strong base hydrolyzes in water to form Options:
  A) A saturated solution
  B) an acidic solution
  C) a buffer solution
  D) an alkaline solution
  Show Answer
  The correct answer is D .
• Question 122: If concentrated sulphric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mas of carbon. In this reaction, concentrated sulphuric acid is acting as ? Options:
  A) a drying agent
  B) an oxidizing agent
  C) a dehydrated agent
  D) a reducing agent
  E) a hydrolysing agent
  Show Answer
  The correct answer is C .
• Question 123: One of the following techniques can be used to show that chlorophyll pigment is a mixture of chemical compounds and not a single coloured compound Options:
  A) cystallization
  B) hydrolysis
  C) sublimation
  D) filtration
  E) chromatography
  Show Answer
  The correct answer is E .
• Question 124:

  At room temperature and standard pressure, chlorine gas is in which state of matter?

  Options:
  A) Plasma
  B) Solid
  C) Liquid
  D) Gas
  Show Answer
  The correct answer is D .
• Question 125: Methane is member of the homologous series called? Options:
  A) alkenes
  B) alcohols
  C) esters
  D) alkanes
  E) alkynes
  Show Answer
  The correct answer is D .
• Question 126: Weighed salts Y and Z were left exposed in the laboratory overnight. In the morning Y had gained weight, and Z had become liquid. What conclusion could be drawn about the nature of the two salts? Options:
  A) Z is efflorescent
  B) Y and Z are efflorescent
  C) Y and Z are deliquescent
  D) Y and Z are hygroscopic
  E) Y is deliquescent
  Show Answer
  The correct answer is C .
• Question 127: Iron is often galvanized in order to Options:
  A) make it more malleable
  B) remove the impurities in it
  C) protect it against corrosion
  D) render it passive
  Show Answer
  The correct answer is C .
• Question 128:

  What volume of oxygen will remain after reacting 8cm of hydrogen gas with 20cm of oxygen gas

  Options:
  A) 10cm${}^3$
  B) 12cm${}^3$
  C) 14cm${}^3$
  D) 16cm${}^3$
  Show Answer
  The correct answer is D .
• Question 129:

  (I). 3CuO(s) + 2NH3(g) -----> 3Cu(s) + 3H2O(l) + N2(g) 

  (II). 2NH3(g) + 3Cl2(g) -----> 6HCl(g) + N2(g) 

  (III). 4NH3(g) + 3O2(g) -----> 6H2O(l) + N2(g) 

  The reactions represented by the equations above demonstrate the

  Options:
  A) basic properties of ammonia
  B) acidic properties of ammonia
  C) reducing properties of ammonia
  D) oxidizing properties of ammonia
  Show Answer
  The correct answer is C .
• Question 130:

  What is the empirical formula of a compound containing 40.00% carbon, 6.67% hydrogen, and 53.33% oxygen by mass?

  Options:
  A) C${}_4$H${}_8$O${}_4$
  B) CH${}_2$O
  C) C${}_2$H${}_4$O${}_2$
  D) C${}_3$H${}_6$O${}_3$
  Show Answer
  The correct answer is B .