Account for
(a) Nitration of benzene is easier than nitration of nitrobenzene
(b) Benzaldehyde undergoes condensation with nitro methane in presence of KOH
(c) Nitromethane gives trichloro nitro methane on treatment with chlorine/NaOH while nitro ethane gives only dichloro ethane

A violet compound of manganese (A) decomposes on heating to liberate oxygen and componds (B) and (C ) of manganese are formed. Compound (C ) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C ) with conc. H_(2)SO_(4) and NaCl, chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds (A)to (D) and also explain the reactions involved.

An organic compound A gives positive test with Tollen's reagent, on treatment with amonia form B which is an eye medicine. A on treatment with concenteated KOH forms C and D. C is on oxidation forms A agains. D on acidification responds to Tollen's Test. A comines with CH_3Mgl followed by hydrolysis forms E, which on oxidation followed by decarboxylation forms methane. Identify A to E (only structure).