Explain the following reactions :

(a)

Wolff Kishner reduction

(b)

Cannizzaro reaction

$\displaystyle {\mathrm{H_3C}\atop\mathrm{H_3C}}\mkern-6mu{\diagdown\atop\diagup}\mkern-4mu\mathrm{C}{=}\mathrm{O} + \mathrm{NH_2NH_2} \longrightarrow {\mathrm{H_3C}\atop\mathrm{H_3C}}\mkern-6mu{\diagdown\atop\diagup}\mkern-4mu\mathrm{C}{=}\mathrm{NNH_2} \xrightarrow[\Delta]{\text{KOH, ethylene glycol}} \mathrm{CH_3{-}CH_2{-}CH_3} + \mathrm{N_2}$

$\displaystyle 2\,\mathrm{HCHO} \xrightarrow{\ \text{conc. KOH}\ } \mathrm{CH_3OH} + \mathrm{HCOO^-K^+}$