Question

an element X show variable valency 4 and 6 chemical formula of its two oxides​

Answer 1

The element showing valency 4 will have 2 electrons in k shell and 4 electrons in L shell. That means we get total 2+4=6 electrons altogether.

We know no. Of electrons = The atomic number of the element.

So the element having atomic number 6 is carbon dioxide (CO2).

Similarly

Element having valency as 6 will have 2 electrons in k shell and 6 electrons in L shell which gives us 2+6=8 electrons altogether.

We know no. of electrons = atomic no. of an element.

So element having atomic no. 8 is oxygen (O2) .

Hope it helps.....