Which among the following reagents is called as Hinsberg's reagent?

Which among the following amines has highest value of $$\mathrm{pK}_{\mathrm{b}}$$ ?

What is vapour pressure of a solution containing $$1 \mathrm{~mol}$$ of a nonvolatile solute in $$36 \mathrm{~g}$$ of water $$\left(\mathrm{P}_1^0=32 \mathrm{~mm} \mathrm{~Hg}\right)$$ ?

Identify the product obtained when phenol is reacted with dilute nitric acid at low temperature.