Write the equations involved in the following reactions
(a) Etard reaction
(b) Wurtz reaction
(c) Williamson’s synthesis

Etard reaction:
$\mathrm{𝑹}-{𝑪𝑯}_{\mathrm{𝟑}}+𝑪𝒓{\mathrm{𝑶}}_{\mathrm{𝟐}}{𝑪𝒍}_{\mathrm{𝟐}} \stackrel{{𝑪𝑺}_{\mathrm{𝟐}} }{\to } \mathrm{𝑹}-𝑪𝑯{\left(𝑶𝑪𝒓𝑶𝑯𝑪{\mathrm{𝒍}}_{\mathrm{𝟐}}\right)}_{\mathrm{𝟐}}\stackrel{{\mathrm{𝑯}}_{\mathrm{𝟑}}{\mathrm{𝑶}}^{+} }{\to } {\mathrm{𝑪}}_{\mathrm{𝟔}}{\mathrm{𝑯}}_{\mathrm{𝟓}}𝑶𝑯$
(b) Wurtz reaction:
$2\mathrm{R}-\mathrm{X}+\mathrm{Na}\stackrel{\text{ dry ether }}{⟶}\mathrm{R}-\mathrm{R}+\mathrm{NaX}$
(c) Williamson’s synthesis;
$\mid \mathbf{R}-\mathbf{X}\stackrel{{\mathbf{RO}}^{-}}{⟶}\mathbf{R}-o-\mathbf{R}+\mathrm{NaBr}$