Waec Chemistry 1990 Past Questions and Answers

Question 16:

• WAEC 1990

The compound of copper which is used in electroplating dyeing, printing, wood preservation and as a fungicide is

A. Copper (ll) hydroxide
B. Copper (ll) trioxonitrate (V) pentahydrate
C. Copper (ll) tetraoxosulphate (VI) pentahydrate
D. Copper (ll) oxide
E. Copper (ll) trioxocarbonate (lV)

Question 17:

• WAEC 1990

What is the molecular formula of a compound whose empirical formula is CH₂O and molar mass is 180? (H = 1, C = 12, O = 16)

A. C ₄H ₈O₂
B. C ₄H ₈O₃
C. C ₆H ₁₀O₅
D. C ₆H ₁₂O₆
E. C ₁₂H ₂₂O₁₁

Question 18:

• WAEC 1990

MO and X ₂O represent the formula of oxides of elements M and X respectively . If M and X should combine to form a separate compound, what would be the formula of the compound?

A. MX₂
B. M₂X
C. MX
D. M₃X₂
E. MX₃

Question 19:

• WAEC 1990

Which of the following pollutants is biodegradable ?

A. Sewage
B. Plastics
C. Metal scrape
D. Lead compounds
E. Hydrogen sulphide

Question 20:

• WAEC 1990

In the reaction represented by the equation; 2FeCI₃ + SO₂ + 2H₂O → 2FeCL₂ + H₂SO₄ + 2HCI the oxidation number of sulphur changes from

A. +2 to + 6
B. + 4 to + 6
C. 0 to + 6
D. - 2 to + 4
E. +2 to + 4