Three elements A, B and C have 3,4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the modern periodic table. Also, give their valencies.

Explanation

To determine the group number and valency of the elements A, B, and C based on the number of valence electrons they have, we can follow these steps:

### Step 1: Identify the number of valence electrons for each element.
- Element A has 3 valence electrons.
- Element B has 4 valence electrons.
- Element C has 2 valence electrons.

### Step 2: Determine the group number for each element.
...