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 671:

  What is the concentration of a solution containing 2g of NaOH in 100cm³ of solution?
  [Na = 23, O = 16, H = 1]

  Options:
  A) 0.40 mol dm^-3
  B) 0.50 mol dm^-3
  C) 0.05 mol dm^-3
  D) 0.30 mol dm^-3
  Show Answer
  The correct answer is B .
• Question 672: Alloys are best prepared by? Options:
  A) high temperature weilding of the metals
  B) electrolysis using the major metallic component as cathode
  C) reducing a mixture of the oxies of the elements
  D) cooling a molten mixture of the necessary elements
  Show Answer
  The correct answer is D .
• Question 673: Solutions X, Y, and Z have PH values 3.0. 5. 0 and 9. 0 respectively. Which of the following statements is correct? Options:
  A) All the solutions are acidic
  B) All the solutions are basic
  C) Y and Z are more acidic than water
  D) Y is more acidic than X
  E) Z is the least acidic
  Show Answer
  The correct answer is E .
• Question 674: Which of the following statements is NOT correct? Options:
  A) The average kinetic energy of a gas is directly proportional to its temperature
  B) At constant tempearture, the volume of a gas increases as the pressure increases
  C) The pressure of a gas is inversely proportional to its volume
  D) The temperature of a gas is directly proportional to its volume
  E) The collisions of molecules with each other are inelastic
  Show Answer
  The correct answer is B .
• Question 675: In which of the following is the oxidation number of sulphur equal to -2? Options:
  A) S₈
  B) H₂S
  C) SO ₂
  D) SO ₃^2-
  Show Answer
  The correct answer is B .
• Question 676:

  Which of the following statements is true for strong electrolytes?

  Options:
  A) They do not conduct electricity in the molten state
  B) They completely dissociate into ions in solution
  C) They are non-polar substances
  D) They partially dissociate into ions in solution
  Show Answer
  The correct answer is B .
• Question 677: The most abundant element on the earth's crust is Options:
  A) nitrogen
  B) hydrogen
  C) oxygen
  D) flourine
  Show Answer
  The correct answer is C .
• Question 678:

  

  In the diagram above, R is a mixture of

  Options:
  A) potassium tetraxochlorate (VII) and concentrated H₂SO₄
  B) potassium trioxochlorate (V) and concentrated H₂SO₄
  C) potassium tetratoxomanganate (VII) and concentrated HCI
  D) manganes (IV) oxide and concentrated HCI
  Show Answer
  The correct answer is D .
• Question 679: How many moles of oxygen molecules would be produced from the decomposition of 2.50 moles of potassium trioxochlorate (V)? Options:
  A) 2.50
  B) 3.50
  C) 3.75
  D) 7.50
  Show Answer
  The correct answer is C .
• Question 680: In the laboratory preparation of chlorine from concentrated hydrochloric acid in the presence of potassuim tetraoxomanganate(VII) the produced is dried by passing it through Options:
  A) Concentrated tetraoxosulphate (VI) acid
  B) Anhydrous calcium chloride
  C) Calcium oxide
  D) Sodium hydroxide
  Show Answer
  The correct answer is A .