What are the group 1a and group 7a elements examples of? my last wuestion

Group 1A  and Group 7A  elements are examples  of  representative  elements

    Explanation

Representative element  - are element in the first two families that is group 1 and 11 element on the far left  of periodic table.In addition  representative element include  the last 6 families  on  the right  side of periodic table.   The representative element include s  and p  blocks element of periodic table.

The answer to this is the 3rd choice!

(no3)⁻n has oxidation number x,o has oxidation number -2.(x*1 -2*3) charge of the nitrate ion, and we know that charge of the nitrate ion =-1.so,(x*1 -2*3) =-1x-6=-1x=+5answer a. +5.