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.

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)

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).

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

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.

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?

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.

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]

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

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.
Given: \({ \lambda }^{ ° }\left( { H }^{ + } \right) \) = 349.5 S cm^-2mol^-1 and \({ \lambda }^{ ° }\left( { HCOO }^{ - } \right) \) = 50.5 S cm²mol^-1

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.