Assertion (A) The boiling points of alkyl halides decrease in the order $$R \mathrm{I}>R \mathrm{Br}>\mathrm{RCl}>\mathrm{RF}$$.
Reason (R) The boiling points of alkyl chlorides, bromides and iodides are considerably higher than that of the hydrocarbon of comparable molecular mass.
Assertion (A) $$\mathrm{N}_2$$ is less reactive than $$\mathrm{P}_4$$.
Reason (R) Nitrogen has more electron gain enthalpy than phosphorus.
Assertion (A) The molecular mass of the polymers cannot be calculated using the boiling point or freezing point method.
Reason (R) The freezing point method is used for determining the molecular mass of small molecules.
Assertion (A) $$\mathrm{NaCl}$$ reacts with concentrated $$\mathrm{H}_2 \mathrm{SO}_4$$ to give colourless fumes with pungent smell. But on adding $$\mathrm{MnO}_2$$ the fumes become greenish yellow.
Reason (R) $$\mathrm{MnO}_2$$ oxidises $$\mathrm{HCl}$$ to chlorine gas which is greenish yellow.