What is meant by ‘doping’ in a semiconductor?

2.

What is the role of graphite in the electrometallurgy of aluminium?

Which one of  is not likely to exist and why?

Arrange the following in the decreasing order of their basic strength in aqueous solutions:

CH₃NH₂, (CH₃)₂NH, (CH₃)₃ N and NH₃

A 1.00 molar aqueous solution of trichloroacetic acid (CCl₃COOH) is heated to its boiling point. The solution has the boiling point of 100.18⁰C. Determine the van’t Hoff factor for trichloroacetic acid. (K_b for water = 0.512 kg mol^-1)

Define the following terms:

 (i) Mole fraction

(ii) Isotonic solutions

(iii) Van’t Hoff factor

 (iv) Ideal solution

What do you understand by the ‘order of a reaction’? Identify the reaction order from each of the following units of reaction rate constant:

(i) L^-1 mol-¹

(ii) L mol^-1 s^-1

Name the two groups into which phenomenon of catalysis can be divided. Give an example of each group with the chemical equation involved.

What is meant by coagulation of a colloidal solution? Describe briefly any three methods by which coagulation of lyophobic sols can be carried out.

Describe the principle involved in each of the following processes.

(i) Mond process for refining of Nickel.

(ii) Column chromatography for purification of rare elements.