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 541: Chlorine consisting of two isotopes of mass number 35 and 37 in the ratio 3:1 has an atomic mass of 35.5. Calculate the relative abundance of the isotopes of mass number 37 Options:
  A) 20
  B) 25
  C) 60
  D) 75
  Show Answer
  The correct answer is B .
• Question 542: An element used in the production of matches is Options:
  A) nitrogen
  B) aluminium
  C) copper
  D) sulphur
  Show Answer
  The correct answer is D .
• Question 543: When sugar is dissolve in ten, the reaction is accomplished by Options:
  A) positive change
  B) negative entropy change
  C) no entropy change
  D) a minimum entropy change
  Show Answer
  The correct answer is C .
• Question 544: The substance often use for vulcanization of rubber is Options:
  A) chlorine
  B) hydrogen peroxide
  C) sulphur
  D) tetraoxosulphate (IV) acid
  Show Answer
  The correct answer is C .
• Question 545: Which of the following compounds of trioxonitrate (V) will decomposes to give dinitrogen (i) oxide and water when heated? Options:
  A) NaNO₃
  B) Zn(NO₃)₂
  C) Cu(NO₃)₂
  D) NH₄NO₃
  Show Answer
  The correct answer is D .
• Question 546: Alloys are often used in preference to pure metals because? Options:
  A) metals are too hard
  B) merals are ductile
  C) metallic properties are improve in alloys
  D) alloys are a mixture of metals
  Show Answer
  The correct answer is C .
• Question 547: A solid X when heated gives off a brown gas. If X is soluble in excess sodium hydroxide solution but insoluble in excess ammonium hydroxide solution, then X is Options:
  A) basic lead carbonate
  B) lead (II) nitrate
  C) sodium carbonate
  D) zinc nitrate
  E) sodium nitrate
  Show Answer
  The correct answer is B .
• Question 548:

  NaCI_(s) + H₂SO_4(I) → HCI_(g) + NaHSO_4(s).

  In the reaction above, H₂SO₄ behaves as?

  Options:
  A) a strong acid
  B) an oxidizing agent
  C) a good solvent
  D) a dehydrating agent
  Show Answer
  The correct answer is A .
• Question 549: A metal that forms soluble trioxosulphate (IV) ion is Options:
  A) barium
  B) potassium
  C) manganese
  D) aluminium
  Show Answer
  The correct answer is B .
• Question 550: A reaction takes places spontaneously if?
  Options:
  A) ∆G = O
  B) ∆S < O and ∆H > O
  C) ∆H < T ∆S
  D) ∆G > O
  Show Answer
  The correct answer is C .