Question

$M$ is a metal above hydrogen in the activity series and its oxide has the formula $M_{2}O$. This oxide when dissolved in water forms the corresponding hydroxide which is a good conductor of electricity. In the above context answer the following:
Name the group to which $M$ belongs.

Answer 1

The valency of O is -2. As 2 atoms of M are combined in $M_{2}O$ the valency of M is +1. Hence , M has 1 electron in its valence shell. If the number of valence electrons are 1 or 2 then the group number is equal to the number of valence electrons. Hence, the group number is 1.