Question

Na3X, Enter the group number of X?

Answer 1

Answer : The group number of X is 15.

Explanation :

In $Na_3X$, 'Na' is a sodium metal and 'X' is an unknown element.

First we have to determine the oxidation state of element 'X'.

Let the oxidation state of element 'X' be, 'a'.

As we know that sodium is an alkali metal which belongs to group 1 and has (+1) charge.

$3(+1)+a=0\\\\+3+a=0\\\\a=-3$

That means, the oxidation state or charge on 'X' is (-3) and the group 15 elements (nitrogen, phosphorous, arsenic, antimony and bismuth) have five electrons in valence shell and thus require three more electrons to acquire the nearest noble gas configuration. Thus, the group 15 elements have the tendency to show (-3) oxidation state.

Hence, the group number of X is 15.

Answer 2

X will be in group 5, since if you exchange the valencies of Na with any element on group 5, you will get Na3X