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 1941: What is the percentage of sulphur in sulphur (IV) oxide? Options:
  A) 66%
  B) 25%
  C) 40%
  D) 50%
  Show Answer
  The correct answer is D .
• Question 1942:

  Na₂CO₃ + 2HCI → 2NaCI + H₂O + CO₂. Using the above equation, what volume of carbondioxide, measured at s.t.p is liberated when 53g of sodium carbonate is dissolved in hydrochloric acid?

  (1 mole of gas occupies 22.4 dm³ at s.t.p)

  (Na = 23, C = 12, O = 16)

  Options:
  A) 44.8 dm³
  B) 11.2 dm³
  C) 100.1 dm³
  D) 3.0 dm³
  E) 22.4 dm³
  Show Answer
  The correct answer is B .
• Question 1943: Chlorine is produced commercially by? Options:
  A) electrolysis of dilute hydrochloric acid
  B) electrolysis of brine
  C) neutralization of hydrogen chloride
  D) heating potassium trioxochlorate (V)
  Show Answer
  The correct answer is B .
• Question 1944: In a neutralization reaction involving HCI and NaOH using litmus as indicator, the colour at the end point is Options:
  A) Blue
  B) Red
  C) Orange
  D) Purple
  Show Answer
  The correct answer is C .
• Question 1945: Which of the reactions occurs at the anode during the electrolysis of a very dilute aqueous solution of sodium chloride? Options:
  A) OH^- - e → OH
  B) CIsup>- - e → CI
  C) OHsup>- + CIsup>-HCI + O₂
  D) Na₊ - esup>- Hg (Na)/(Hg) amalgam
  Show Answer
  The correct answer is A .
• Question 1946:

  Which group does calcium belong to in the periodic table?

  Options:
  A) Alkaline earth metals
  B) Halogens
  C) Alkali metals
  D) Noble gases
  Show Answer
  The correct answer is A .
• Question 1947: MnO_4(aq) + 8H + _(aq) + 5Fe²⁺ → Mn^2+(aq) + 4H₂O_(I). The oxidation number of manganese in the above reaction changed from? Options:
  A) +7 to +2
  B) +6 to +2
  C) +5 to +2
  D) +4 to +2
  Show Answer
  The correct answer is A .
• Question 1948:

  How many pi ($\pi$) bonds are there in an alkene with six carbon atoms?

  Options:
  A) 4
  B) 6
  C) 5
  D) 3
  Show Answer
  The correct answer is D .
• Question 1949: When dissolved in water, NaOH flakes show Options:
  A) An endothermic change
  B) An exothermic change
  C) A slow reaction
  D) A rapid reaction
  Show Answer
  The correct answer is B .
• Question 1950:

  A gaseous metallic chloride MCl consists of 20.22% of M by mass. The formula of the chloride is?

  [ M = 27, Cl = 35.5]

  Options:
  A) MCl
  B) MCl${}_2$
  C) MCl${}_3$
  D) M${}_2$Cl${}_6$
  Show Answer
  The correct answer is C .