Question

Choose from the following elements whose atomic numbers are given in parentheses H(1), He(2), C(6), F(9), Na(11), Cl(17), Mg(12)
a) Smallest element of 3rd period.
b) A noble gas.
c) A metal of 3rd period having valency 1. d) Most non metallic element of 2nd period.

Answer 1

smallest element of 3rd period will be Na (11).
and noble gas will be He(2).

Answer 2

a) Na(11)

b) He(2)

c) Na (11)

d) F (9)