Waec Chemistry 1990 Past Questions and Answers

Question 21:

• WAEC 1990

Which of the following equations represents the reaction leading to the removal of permanent hardness of water?

A. Ca(HCO ₃)₂ → CaCO₃ + H₂O + CO₂
B. MgSO₄ + Na ₂CO₃ + Na ₂SO
C. Ca(OH) ₂ + 2HCI → CaCI ₂ + 2H ₂O
D. Ca(HCO₃)₂ + Ca(OH)₃ → 2CaCO₃ + 2H₂O
E. MgSO₄ + BaCI₂ → MgCI₂ + BaSO₄

Question 22:

• WAEC 1990

The following alloys contain copper except

A. Magnalium
B. Duralumn
C. Bronze
D. Brass
E. Type metal

Question 23:

• WAEC 1990

How many mole of AgNO ₃ are there in 500cm³ of 0.01MAgNO₃ solution?

A. 0.005 mole
B. 0.05 mole
C. 0.5 mole
D. 5 moles
E. 1 mole

Question 24:

• WAEC 1990

Which of the following statements explains why tetraoxosulphate (IV) acid is reqarded as a strong acid?

A. Tetraoxosulphate (IV) acid is dibasic
B. The acid is concentrated
C. The acid is complately ionized in aqueous solution
D. Tetraxosulphate (IV) ions are very reactive
E. The acid is highly corrosive

Question 25:

• WAEC 1990

Which of the following is not correct of glucose and fructose?They

A. Are structural isomers
B. Reduce fehling's solution
C. Can be obtained by the hydrolysis of starch
D. Are readily fermented by enzymes
E. Are soluble in water