(A) has intramolecular H-bonding and (B) has intermolecular H-bonding
Intramolecular hydrogen bonding in o-hydroxybenzaldehyde (A) results in a less rigid structure compared to p-hydroxybenzaldehyde (B), where intermolecular hydrogen bonding leads to a higher degree of molecular association and therefore a higher melting point.
From the given following (A to D) cyclic structures, those which will not react with Tollen's reagent are : 
Compound 'P' undergoes the following sequence of reactions : (i) NH₃ (ii) $\Delta$ $\rightarrow$ Q (i) KOH, Br₂ (ii) CHCl₃, KOH (alc), $\Delta$ $\rightarrow$ NC-CH₃. 'P' is : 
