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 1141:

  When large hydrocarbon molecules are heated at high temperature in the presence of a catalyst to give smaller molecules, the process is known as

  Options:
  A) disintegration
  B) polymerization
  C) cracking
  D) degradation
  Show Answer
  The correct answer is C .
• Question 1142: ${}_{88}^{226}Ra$ → ${}_{86}^{x}Rn$ + alpha particle Options:
  A) 226
  B) 220
  C) 227
  D) 222
  Show Answer
  The correct answer is D .
• Question 1143:

  Consider the reaction: A + 2B${}_{(g)}\rightleftharpoons$ 2C + D${}_{(g)}$ ($\mathrm{\Delta }$H = +ve)

  What will be the effect of decrease in temperature on the reaction?

  Options:
  A) Rate of backward reaction will increase
  B) The equilibrium constant will shift
  C) Rates of forward and backward reactions are not affected
  D) Rate of forward reaction will increase
  Show Answer
  The correct answer is A .
• Question 1144:

  What volume of gas is evolved at S.t.p if 2g of calcium trioxocarbonate (IV) is added to a solution of hydrochloric acid?

  [Ca = 40, C = 12, O = 16, Cl = 35.5, H = 1 Molar volume of agas at s.t.p = 22.4 dm³

  Options:
  A) 112 cm²
  B) 224 cm²
  C) 448 cm²
  D) 2240 cm²
  Show Answer
  The correct answer is C .
• Question 1145:

  Addition of charcoal to the filter bed of sand during water treatment for township supply is to?

  Options:
  A) prevent goiter
  B) prevent tooth decay
  C) remove odour
  D) kill germs
  Show Answer
  The correct answer is C .
• Question 1146:

  An isotope has an atomic number of 15 and a mass number of 31. The number of protons it contains is

  Options:
  A) 16
  B) 15
  C) 46
  D) 31
  Show Answer
  The correct answer is B .
• Question 1147: A metal that can be extracted from cassitertite is Options:
  A) cacium
  B) magnesium
  C) tin
  D) copper
  Show Answer
  The correct answer is C .
• Question 1148:

  If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density.

  Options:
  A) 196
  B) 49
  C) 106
  D) 82
  Show Answer
  The correct answer is B .
• Question 1149:

  

  The diagram above represents an atom that can combine with chlorine to form

  Options:
  A) a covalent bond
  B) an electrovalent bond
  C) a hydrogen bond
  D) a co-ordinate bond
  Show Answer
  The correct answer is B .
• Question 1150:

  Which of the compounds is composed of Al, Si, O and H?

  Options:
  A) Epson salt
  B) Limestone
  C) Clay
  D) Urea
  Show Answer
  The correct answer is C .