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 391:

  A solution X, on mixing with AgNO${}_3$ solution gives a white precipitate soluble in aqueous NH${}_3$, a solution Y, when also added to X, also gives a white precipitate which is soluble when heated solutions X and Y respectively contain

  Options:
  A) Al${}^{3+}$, Cl${}^{-}$
  B) Hg${}^{+}$, SO${}_4^{2-}$
  C) Pb${}^{2+}$, Cl${}^{-}$
  D) Ag${}^{+}$, SO${}_4^{2-}$
  Show Answer
  The correct answer is C .
• Question 392: What is the consequences of increasing pressure on the equilibrium reaction ZnO_(s) + H_2(g) Zn_(s) + H₂O_(I)? Options:
  A) The equilibrium is driven to the left
  B) The equilibrium is driven to the right
  C) There is no effect
  D) More ZnO is produced
  Show Answer
  The correct answer is C .
• Question 393:

  CO_(g) + H₂O_(g) → CO_2(g) + H_2(g)

  From the reaction above, calculate the standard enthalpies of formation of CO_2(g), H₂O_(g) and CO_(g) in kJ mol^-1 are -394, -242, and -110 respectively.

  Options:
  A) -262 kJ mol^-1
  B) -42 kJ mol^-1
  C) +42 kJ mol^-1
  D) +262 kJ mol^-1
  Show Answer
  The correct answer is B .
• Question 394: An organic compound containing 40.1% carbon and 6.6% hydrogen has an empirical formula of? Options:
  A) C₂H₄O₂
  B) C₂H₃O₂
  C) CH₂O
  D) CH₃O
  Show Answer
  The correct answer is C .
• Question 395:

  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 .
• Question 396:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 397: The arrangement of particles in crystal lattices can be studied using Options:
  A) X-rays
  B) $\beta$-rays
  C) $\alpha$-rays
  D) $\gamma$-rays
  Show Answer
  The correct answer is A .
• Question 398: Which of the following is a neutralization reaction? Options:
  A) Addition of sodium chloride solution to potassium chloride solution
  B) Addition of trioxonitrate (V) acid (nitric acid) to distilled water
  C) Addition of trioxonitrate (V) acid (nitric acid) to tetraoxosulphate (IV) acid (sulphuric acid)
  D) Addition of trioxonitrate (V) acid (nitric acid) to potassium trioxonitrate (V) (potassium nitrate) solution
  E) Addition of trioxonitrate (V) acid (nitric acid) to potassium hydroxide solution
  Show Answer
  The correct answer is E .
• Question 399: A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is? Options:
  A) sulphur (ii) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
  Show Answer
  The correct answer is A .
• Question 400:

  The choice of method for extracting a metal from its ores depends on the

  Options:
  A) strength of the core
  B) position of the metal in the electrochemical series
  C) source of the core
  D) position of the metal in the periodic table
  Show Answer
  The correct answer is B .