(a)(i) State one physical method and one chemical method in each case by which the following can be removed:

I. Permanent hardness in water

II. A suspension of CaCO\(_3\) in water.

(ii) Give one disadvantage of hard water.

 

(b) Explain the following observations: (i) Crystals of washing soda become powdery on exposure to air for a long time

(ii) The concentration of chloride ions in 0.02 mol dm\(^{-3}\) calcium chloride solution is not the same s in 0.02 mol dm\(^{-3}\) sodium chloride solution.

(iii) Iron filings corrode faster than iron nails of the same mass.

 

(c)(i) Classify each of the following oxides as acidic, basic, neutral or amphoteric. I. ZnO II. CO III. NO\(_2\)

(ii) Give the formula of the acid anhydride of each of the following: I. H\(_2\)CO\(_3\) II. H\(_2\)SO\(_4\)

(iii) Give the IUPAC name of the following salts: I. COCl\(_2\) II. Mg(NO\(_3\))\(_2\).

 

(d)(i) Mention one pollutant associated with depletion of ozone layer in the atmosphere

(ii) Calculate the volume occupied by 0.125 mole of oxygen at 27°C and a pressure of 2.02 x 105 Nm\(^{-2}\) [I mole of gas occupies 22.4 dm\(^3\) at s.t.p; standard pressure = 1.01 x 105 Nm\(^{-2}\)]

(iii) State one process used for the industrial preparation of oxygen.