Hướng dẫn:

${{n}_{{{C}_{2}}{{H}_{5}}OH}}={{V}_{{{C}_{2}}{{H}_{5}}OH}}.{{C}_{M}}_{_{{{C}_{2}}{{H}_{5}}OH}}=0,2.0,5=0,1\left( mol \right)$

  $2{{C}_{2}}{{H}_{5}}OH+2Na\to 2{{C}_{2}}{{H}_{5}}ONa+{{H}_{2}}\uparrow $

     0,1        $\to $ 0,1                                                     (mol)

Theo phương trình ta có: ${{n}_{Na}}=\frac{2.{{n}_{{{C}_{2}}{{H}_{5}}OH}}}{2}={{n}_{{{C}_{2}}{{H}_{5}}OH}}=0,1\left( mol \right)$

$\Rightarrow {{m}_{Na}}={{n}_{Na}}.{{M}_{Na}}=0,1.23=2,3\left( g \right)$

$\Rightarrow $Chọn đáp án A