What type of colloid is formed when a liquid is dispersed in a solid? Give an example.

(a) Give reasons for the following:

(i) Sulphur in vapour state shows paramagnetic behaviour

(ii) N-N bond us weaker than P-P bond

(iii) Ozone is thermodynamically less stable than oxygen.

(b) Write the name of gas released when Cu is added to

(i) Dilute HNO₃

(ii) Conc. HNO₃

OR

(a) Answer the following:

(i) Write the disproportionation reaction of H₃PO₃

(ii) Draw the structure of XeF₄

(b) Account for the following:

(i) Although fluorine has less negative electron gain enthalpy yet F₂ is strong oxidising agent.

(ii) Acidic character decreases from N₂O₃ to Bi₂O₃

(c) Write a chemical reaction to test sulphur dioxide gas. Write chemical equation involved.

Arrange the following in increasing order of pK_b values: C₆H₅CH₂NH_2, C₆H₅CH₂NHCH₃, C₆H₅NH₂

Out of chlorobenzene and p-nitrochlorobenzene, which one is more reactive towards nucleophilic substitution reaction and why?

Give reasons:

(a) A decrease in temperature is observed on mixing ethanol and acetone.

(b) Potassium chloride solution freezes at a lower temperature than water.