Chemistry Past Questions and Answers

Which of the following ions is a pollutant in drinking water even in trace amounts?

A Ca²⁺
B Hg²⁺
C Mg²⁺
D Fe²⁺

Question 17:

The solubility of copper (II) tetraoxosulphate (Iv) is 75g in 100g of water at 100°C and 25g in 100g of water at 30°C. What mass of the salt would crystallize, if 50g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C ?

A 57.5
B 42.2
C 28.6
D 14.3

Question 18:

A sample of temporary hard water can be prepared in the laboratory by?

A Disolving calcium chloride in distilled water
B Saturating lime water with carbon (IV) oxide
C Saturating distilled water with calcium hydroxide
D Dissolving sodium hydrogen trioxocarbonate (IV) in some distilled water

Question 19:

A property of a colloidal dispersion which a solution does not have is?

A The Tyndall effect
B Homogeneity
C Osmotic pressure
D Surface polarity

Question 20:

50 cm³ of sulphur (IV) oxide, 800 cm³ of ammonia, 450 cm³ of hydrogen chloride, 1.0 cm³ of at 15°C. Which of the following is suitable for demonstrating the fountain experiment?

A Sulphur (IV) oxide hydrogen chloride
B Carbon (IV) oxide and amonia
C Amonia and hydrogen chloride
D Carbon (IV) oxide and surphur (IV) oxide