Waec Chemistry Past Questions For Year 2002

Question 26

The gas given off when NH₄ Cl is heated with an alkali is

waec 2002

• A. H₂
• B. Cl₂
• C. N₂
• D. NH₃

Question 27

Equal amounts of marble chips are reacted separately with 100cm³ of hydrochloric acid of different concentrations. If all the marble chips reacted; which of the following remained the same in each case?

waec 2002

• A. Average rate of evoluton of gas
• B. Total mass of gas evolved during the reaction
• C. Time taken for the reaction to reach completion
• D. Initial reaction rates

Question 28

What is the expression for the equilibrium constant (K_c) for the following reaction? N_2(g) + O_2(g) ⇌ 2NO_(g)

waec 2002

• A. \(\frac{[NO^2]}{[N^2] + [O^2]}\)
• B. \(\frac{[2NO]^2}{[N_2][O_2]}\)
• C. \(\frac{[N_2] + [O_2]}{2[NO]^2}\)
• D. \(\frac{[NO]^2}{[N_2][O^2]}\)

Question 29

What will happen if more heat is applied to the following system at equilibrium?

X\(_2\)(g) + 3Y\(_2\)(g) ⇌ 2XY\(_3\)(g); ∆H = xKJmol\(^{-1}\)

waec 2002

• A. the yield of XY ₃ will decompose
• B. more of XY₃ will decompose
• C. More of X₂ will react
• D. the forward reaction will remain static

Question 30

Which of the following salt solutions will have a pH greater than 7?

waec 2002

• A. NaCI_(aq)
• B. Na₂CO_3(aq)
• C. Na₂SO_4(aq)
• D. NaHSO_4(aq)