Which of the following on treatment with warm dil. ${\mathrm{H}}_2{\mathrm{SO}}_4$ in presence of ${\mathrm{HgSO}}_4$ will give a methyl ketone

Among P, Q, R and S, the aromatic compound(s) is (are)

Which of the following undergo electrophilic substitution reactions faster than benzene?

The total number of stable conformers with non-zero dipole moment for the following compound is/are

How many of the given molecules have zero dipole moment?

cis-$1,2$-dichloroethene, trans-$1,2$-dichloroethene, $1,1$-dichloroethene, trans-$2$-pentene, cis-$2$-pentene, $1$-butyne, trans-$2$-butene, cis-$2$-butene.