Columns 1, 2 and 3 contain starting materials, reaction conditions, and type of reactions, respectively.

	Column 1		Column 2		Column 3
(I)	Toluene	(i)	NaOH/Br2	(P)	Condensation
(II)	Acetophenone	(ii)	Br2/hv	(Q)	Carboxylation
(III)	Benzaldehyde	(iii)	(CH3CO)2O/ CH3COOK	(R)	Substitution
(IV)	Phenol	(iv)	NaOH/CO2	(S)	Haloform

The only CORRECT combination in which the reaction proceeds through radical mechanism is :

The sum of the number of lone pairs of electrons on each central atom in the following species is

$${[TeB{r_6}]^{2 - }},{\left[ {Br{F_2}} \right]^ + },SNF_3,$$ and $${\left[ {Xe{F_3}} \right]^ - }$$

(Atomic numbers: $$N = 7,F = 9,$$ $$S = 16,Br = 35,$$ $$Te = 52,Xe = 54$$)

The conductance of a $$0.0015$$ $$M$$ aqueous solution of a weak monobasic acid was determined by using a conductivity cell consisting of platinized $$Pt$$ electrodes. The distance between the electrodes is $$120$$ $$cm$$ with an area of cross section of $$1$$ $$c{m^2}.$$ The conductance of this solution was found to be $$5 \times {10^{ - 7}}S.$$ The $$pH$$ of the solution is $$4.$$ The value of limiting molar conductivity $$\left( {\Lambda _m^o} \right)$$ of this weak monobasic acid in aqueous solution is $$Z \times {10^2}S$$ $$c{m^2}$$ $$mo{l^{ - 1}}.$$ The value of $$Z$$ is

A crystalline solid of a pure substance has a face-centered cubic structure with a cell edge of $$400$$ $$pm.$$ If the density of the substance in the crystal is $$8$$ $$g\,c{m^{ - 3}},$$ then the number of atoms present in $$256$$ $$g$$ of the crystal is $$N \times {10^{24}}.$$ The value of $$N$$ is