Question

From the following:-

4Be, 9F, 19K, 20Ca

1.Select the element having 1 electron in the outer most shell.

2.Two elements of the same group.

Answer 1

electronic configurations:
Be : (2,2)
F : (2,7)
K: (2,8,8,1)
Ca: (2,8,8,2)

so, 1) K
2) K, Ca