Assign reasons for the following:

(i) Phosphorus doped silicon is a semiconductor.

(ii) Schottky defect lowers the density of a solid.

(iii) Some of the very old glass objects appear slightly milky instead of being transparent.

3

(a)

Silver forms ccp lattice and X-ray studies of its crystals show that the edge length of its unit cell is 408.6 pm. Calculate the density of silver (Atomic mass=107.9 u)

3

(a)

Conc. H₂SO₄ has a density of 1.9 gmL^-1 and is 99 % by weight. calculate the molarity of is 99% by weight. Calculate the molarity of H₂SO₄ (Mol . Wt pf H₂SO₄ = 98 g mol^-1).

3

(a)

A 5% solution of cane-sugar (m.wt. = 342) is isotonic with 0.877% solution of urea. Find the molecular weight of urea.

3

(a)

What is a nickel-cadmium cell? State its one merit and one demerit over lead storage cell. Write the overall reaction that occurs during discharging of this cell.

3

(a)

State and explain Kohlrausch's law of independent migration of ions. How can the degree of dissociation of acetic acid be calculated from its molar conductance data?

3

(a)

Crude copper containing Fe and Ag as contaminations was subjected to electro refining by using a current of 175 A for 6.434 min. The mass of anode was found to decrease by 22.260 g, while that of cathode was increased by 22.011 g. Estimate the % of copper, iron and silver in crude copper.

3

(a)

Show that in case of first order reaction, the time required for 99.9% of the reaction to complete is 10 times that required for half of the reaction to take place.

[log 2 = 0.301]

3

(a)

The rate constants of a reaction at 500K and 700K are 0.02s^-1 respectively.Calculate the values of E_a and A

3

(a)

What is the criterion for choosing a method of reduction? Explain with Ellingham’s diagram, by taking at least 2 examples.

3

(a)

Identify the first row transition metal ions which have outer electronic configurations of 3d⁴ and 3d⁶ and describe their oxidation states. 

3

(a)

Write the structures of A, B and C

3

(a)

Low level of noradrenaline is the cause of depression. What type of drugs are needed to cure this problem? Name two drugs.

3

(a)

Conductivity of \(2.5\times { 10 }^{ -4 }\)M methanoic acid is \(5.25\times { 10 }^{ -5 }S{ cm }^{ -1 }\)
Calculate its molar conductivity and degree of dissociation.

3

(a)

An alkene 'A' (Mol.  formula C₅H₁₀) on ozonolysis gives a mixture of two compounds 'B' and 'C'.  Compound 'B' gives positive Fehling's test and also forms iodoform on treatment with I₂ and NaOH.  Compound 'C' does not give Fehling's test but forms iodoform.  Identify the compounds A, B and C.  Write the reaction for ozonolysis and formation of iodoform from B and C.

3

(a)