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 821: An increase in temperature causes an increase in the pressure of a gas because there is an increase in the? Options:
  A) average velocity of the molecules
  B) number of collisions between the molecules
  C) density of the molecules
  D) free mean path between each molecules and other
  Show Answer
  The correct answer is B .
• Question 822: Hydrogen sulphide gas can act as Options:
  A) an oxidizing agent
  B) a dehydrating agent
  C) a bleaching agent
  D) a precipitating agent
  Show Answer
  The correct answer is D .
• Question 823: The brown fumes given off when trioxonitrate (V) acid is heated consist of ? Options:
  A) NO₂ and O₂
  B) H₂O and NO₂
  C) NO_2' O₂ and H₂O
  D) NO, NO₂ and H₂O
  Show Answer
  The correct answer is C .
• Question 824: Which of the following hydrogen halides the highest entropy value? Options:
  A) HF
  B) HCl
  C) HBr
  D) HI
  Show Answer
  The correct answer is A .
• Question 825:

  Alkanol + Alkanoic ↔ Ester + Water

  The reverse reaction above is known as

  Options:
  A) Hydrolysis
  B) Saponification
  C) Hydration
  D) Fermentation
  Show Answer
  The correct answer is A .
• Question 826: The reddish–brown rust on ion roofing sheets consists of Options:
  A) Fe³ + (H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H2₂O
  Show Answer
  The correct answer is C .
• Question 827:

  The volume occupied by 1.58g of a gas at S.T.P is 500cm${}^3$. What is the relative molecular mass of the gas?  [ G.M.V at S.T.P = 22.4dm${}^3$ ]

  Options:
  A) 28
  B) 32
  C) 44
  D) 71
  Show Answer
  The correct answer is D .
• Question 828:

  Na₂CO_3(g) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l) + CO_2(g)

  How many moles of sodium trioxocarbonate (IV) are there in a 25 cm³ solution which required 10cm³ of 0.05 mol dm^-3 hydrochloric acid solution to neutralize it?

  Options:
  A) 1.000 mole
  B) 0.100 mole
  C) 0.010 mole`
  D) 0.111 mole
  Show Answer
  The correct answer is C .
• Question 829: Copper (II) tetraoxosulphate (VI) solution is electrolyzed using carbon electrodes. Which of the following are produced at the anode and cathode respectively ? Options:
  A) Copper and oxygen
  B) Oxygen and copper
  C) Hydrogen and copper
  D) Copper and hydrogen
  Show Answer
  The correct answer is B .
• Question 830:

  The most abundant rare gas in the atmosphere is?

  Options:
  A) He
  B) Ne
  C) Ar
  D) Xe
  Show Answer
  The correct answer is C .