Which of the following compounds would undergo aldol condensation?

The product $(A)$ of the following reaction is (bromination does not occur in the benzene ring):

$CH_3-CO-CH_2-CH_2-CH_2-CH_2-CHO \xrightarrow{KOH} ?$ The number of intramolecular aldol condensation products is:

Which of the following is used to detect aldehydes?

Compound $(A)$ with molecular formula $C_6H_{12}O_3$ gives a positive iodoform test and a negative Tollens' test. Upon treatment with water and a drop of $H_2SO_4$,it gives a positive Tollens' test. Compound $(A)$ is:

Reaction of iso-propylbenzene with $O_2$ followed by treatment with $H_3O^{+}$ forms phenol and a by-product $P$. Reaction of $P$ with $3$ equivalents of $Cl_2$ gives compound $Q$. Treatment of $Q$ with $Ca(OH)_2$ produces compound $R$ and calcium salt $S$. The correct statement(s) regarding $P, Q, R$ and $S$ is(are):
$(A)$ Reaction of $P$ with $R$ in the presence of $KOH$ gives chloritone.
$(B)$ Reaction of $R$ with $O_2$ in the presence of light gives phosgene gas.
$(C)$ $Q$ reacts with aqueous $NaOH$ to produce $Cl_3CCH_2OH$ and $Cl_3CCOONa$.
$(D)$ $S$ on heating gives $P$.