10.27 State as to why (a) a solution of Na2CO3 is alkaline ? (b) alkali metals are prepared by electrolysis of their fused chlorides ? (c) sodium is found to be more useful than potassium ?

$Na_{2}CO_{3}+H_{2}O\rightarrow NaOH+ H_{2}CO_{3}$
$(2M+H_{2}O\rightarrow 2M^{+}+2OH^{-}+H_{2})$ [M = alkali metals]