Predict the valencies of the elements with atomic numbers 7 , 15 , 16 , 18 , 19 and justify Also give the formulae of hydrides formed by the above elements if any.

Explanation

Since N and P need three more electrons to attain octet , their valencies are 3. Similarly , the valencies of other elements with atomic number 16 , 18 , 19 are 2 , 0 and 1 respectively.
Except argon , all other elements forms hydrides.
Phosphorus `- PH_(3)`, Potassium - KH
Nitrogen `NH_(3)`
Sulphur `- H_(2)S`
Argon does not from any compound