Waec Chemistry Past Questions and Answers

Question 36:

• WAEC 1988

Which of the following correctly explains why iodine crystals change directly into the gaseous state when heated?

A. Lodine crystals sublime
B. Lodine atoms are held together by strong forces
C. Lodine molecules are held together by weak forces
D. Lodine molecules are covalent
E. Lodine is a solid at room temperature

Question 37:

• WAEC 1988

Which of the following is a waste product in the Solvary Process for the manufacture of sodium trioxocarbonate (IV)?

A. Ammonium chloride
B. Brine
C. Limestone
D. Calcium oxide
E. Calcium chloride

Question 38:

• WAEC 1988

When copper (ll) chloride solution is treated with excess aqueous ammonia, a deep blue solution results This is due to the presence of

A. (CuNH₄)³⁺ ions
B. (CuCI₄)^2-ions
C. [Cu(OH)₄]^2- ions
D. Cu(H^2-O)₄²⁺ IONS
E. [cU(NH₃)₄] ^ions

Question 39:

• WAEC 1988

The complex salt formed when aluminium dissolves in sodium hydroxide solution is

A. Na₃AI(OH)₄
B. Na₂AI(OH)3
C. NaAI(OH)₃
D. Na₄AI(OH)₄
E. NaAI(OH)₄

Question 40:

• WAEC 1988

The reaction represented by the equation C_(s) + H₂O_(l) → CO_(s) + H _2(s) was carried out at 27_oC if the enthalpy change was + 4500 J and the entropy change was + 12J, what was the free energy change? (∆G = ∆H - T∆S)

A. - 4176 J
B. +4176 J
C. - 900 J
D. + 900 J
E. +8100 J