Tarnished silver contains Ag₂ S. Can this tarnish be removed by placing tarnished silver ware in an aluminium pan containing an inert electrolytic solution such as NaCl ? The standard electrode potential for the half reactions are : For \({ Ag }_{ 2 }S(s)+{ 2e }^{ - }\longrightarrow 2Ag(s)+{ S }^{ 2- },\) it is - 0.71 V and for \({ Al }^{ 3+ }+{ 3e }^{ - }\longrightarrow Al(s)\), it is - 1.66 V

For the reaction, N₂O₅(g) = 2 NO₂(g) + 0.5 O₂ (g), calculate the mole fraction of N₂O₅ (g) decomposed at a constant volume and temperature, if the initial presure is 600 mm Hg and the pressure at any time is 960 mm Hg. Assume ideal gas behaviour.

Explain the following in one or two sentences
(i) Displacement of cyanic and amide ion is never observed in nucleophilic substitution reactions.
(ii) RCI is hydrolysed to ROH slowly but the reaction is rapid if a catalytic amount of KI is added to the reaction mixture.

2,2-Dimethyloxirane can be cleaved by acid (H⁺).Write its mechanism.

Give reason for the following :
(i) On electrolysis in acidic solution, aminoacids migrate towards cathode while in alkaline solution these migrate towards anode.
(ii) The mononamino monocarboxylic acids have two pK values.

A one  - litre vessel contained a gas at 27^oC. 6 g of charcoal was introduced into it. The pressure of the gas fell down from 700 mm to 400 mm. Calculate the volume of the gas (at S.T.P) adsorbed per gram of charcoal. Density of charcoal sample used was 1.5 g cm^-3 .

An organic compound (A) on treatment with CHCl₃ and KOH gives two compounds B and C.Both B and C give the same product (D) when distilled with zinc dust.Oxidation of D gives E having molecular formula C₇H₆O₂.The sodium salt of E on heating with soda-lime gives F which may also be obtained by distilling A with zinc dust.Identify A to F