A solution 0.1 M of Na₂SO₄ is dissolved to the extent of 95%. What would be its osmotic pressure at 27^oC? (R = 0.0821 L atm K^-1 mol^-1)

Define the following with a suitable example, of each:

a. Coagulation

b. Multimolecular colloid

c. Gel

OR

a. Out of starch and ferric hydroxide sol, which one can easily be coagulated and why?

b. What is observed when an emulsion is centrifuged?

c. What is the role of promoters and poisons in catalysis?

a. An element crystallises in bcc lattice with a cell edge of 3×10^-8 cm. The density of the element is 6.89 g cm^-3. Calculate the molar mass of the element. (N_A = 6.022 ×× 10²³ /mol)

b. What type of semiconductor is obtained when

i. Ge is doped with In?

ii. Si is doped with P?

Write down the reactions taking place in blast furnace related to the metallurgy of iron in the temperature range 500 K – 800 K. What is the role of limestone in the metallurgy of iron?

OR

What happens when

a. Silver is leached with NaCN in the presence of air?

b. Copper matte is charged into silica lined converter and hot air blast is blown?

c. NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method?

Give reasons for the following:

a. Dioxygen is a gas but sulphur a solid.

b. NO (g) released by jet aeroplanes is slowly depleting the ozone layer.

c. Interhalogens are more reactive than pure halogens.