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 951: A gas X diffuses twice as fast as gas Y. if the relative molecular mass of X is 32, calculate the relative molecular mass of Y. Options:
  A) 128
  B) 8
  C) 16
  D) 64
  Show Answer
  The correct answer is A .
• Question 952: Moving from left to right across a period, the general rise in the first ionization energy can be attributed to the Options:
  A) decrease in nuclear charge
  B) increase in nuclear charge
  C) decrease in screening effect
  D) increase in screening effect
  Show Answer
  The correct answer is B .
• Question 953: In the purification of town water supply, alum is used principally to? Options:
  A) kill bacteria
  B) control the pH of water
  C) improve the taste of the water
  D) coagulate small pasrticles of mud
  Show Answer
  The correct answer is D .
• Question 954: Indicate which of the following statements is not true as we move from left to right along the periodic Table: Options:
  A) atomic number of elements increases
  B) atomic mass of elements increases
  C) electropositive character of elements increases
  D) electronegative character of elements increases
  E) number of electrons in the outermost orbits of element increases
  Show Answer
  The correct answer is C .
• Question 955: In which of the following is the entropy change positive? Options:
  A) Thermal dissociation of ammonium chloride
  B) Reaction between an acid and a base
  C) Addition of concentrated acid to water
  D) Dissolution of sodium metal in water
  Show Answer
  The correct answer is A .
• Question 956: Which of the following types of bonding does not involve the formation of new substance? Options:
  A) Metallic
  B) covalent
  C) Co-ordinate
  D) Electrovalent
  Show Answer
  The correct answer is A .
• Question 957:

  3Cu + pHNO₃ →3Cu(NO)₂ + 4H₂ O + xNO

  In the equation above, the values of p and x respectively are

  Options:
  A) 1 and 3
  B) 2 and 3
  C) 6 and 2
  D) 8 and 2
  Show Answer
  The correct answer is D .
• Question 958:

  An example of a polysaccharide is?

  Options:
  A) Dextrose
  B) Mannose
  C) Glucose
  D) Starch
  Show Answer
  The correct answer is D .
• Question 959: Which of the following methods may be used to prepare trioxonitrate (V) acid (nitric acid) in the laboratory? Options:
  A) Heating ammonia gas with tetraoxosulphate (VI) acid
  B) Heating ammonium trioxonitrate (V) with tetraoxosulphate (VI) acid
  C) Heating sodium trioxonitrate (V) with tetraoxosulphate (VI) acid
  D) Heating potassium trioxonitrate (V) with calcium hydroxide
  E) Heating a mixture of ammonia gas and oxygen.
  Show Answer
  The correct answer is C .
• Question 960: The petroleum fraction that is used in heating furnaces in industries is Options:
  A) diesel oil
  B) gasoline
  C) kerosene
  D) lubricating oil
  Show Answer
  The correct answer is A .