Question

two elements which have only two electrons in their outermost shell

Answer 1

its helium and magnesium
hope it helps

Answer 2

The group number is equal to the number of electrons in the outermost shell. Hence, 2nd group elements have 2 electrons in their outermost shell.

2nd group elements are as follows:

Beryllium(Be)

Magnesium(Mg)

Calcium(Ca)

Strontium(Sr)

Barium(Ba)

Radium(Ra)