Answer: Option (a) is the correct answer.
Explanation:
A metal is a substance which loses electron(s) in order to attain stability.
For example, sodium is an alkali metals with atomic number 11 and its electronic distribution is 2, 8, 1.
So, in order to attain stability sodium will readily lose 1 electron and forms [tex]Na^{+}[/tex] ion.
Whereas non-metals are the substances which gain electron(s) in order to attain stability.
For example, atomic number of carbon is 6 and its electronic configuration is 2, 4.
To attain stability a carbon atom shares it 4 valence electrons with another atom.
Thus, we can conclude that out of the given options, Na is a metal.
