Use the periodic table to answer the following questions.
(a) Identify an element with five electrons in the outer subshell.
(b) Identify an element that would tend to lose two electrons.
(c) Identify an element that would tend to gain two electrons.
(d) Identify the group having metal, non-metal, liquid as well as gas at the room temperature.

Explanation

a. The general electronic configuration of the elements having five electrons in the outer subshell is `ns^(2)np^(5)`.This electronic configuration is characteristic of elements of group `17` i.e. hallogens and their examples are `F`,`Cl`,`Br`,`I`,`At`,etc.
b. The elements which have a tendency to lose two electrons must have two electrons in the valence shell. Therefore, their general configuration should be `ns^(2)`. This electronic configuration is characterstic of group `2` elements, i.e. alkaline earth metals and their examples are `Mg`,`Ca`,`Sr`,`Ba`, etc.
c. The elements which have a tendency to accept two electrons must have four electrons in the valence shell. Therefore, their general electronic configuration is `ns^(2)np^(4)`. This electronic configuration is characteristic of group `16` elements and their examples are `O`,`S`,`Se`,`Te` etc.
d. A metal which is liquid at room temperature is mercury. It is a transition metal and belongs to group `12`. A non-metal which is a gas at room temperature is nitrogen (group 15),oxygen (group 16),flurine, chlorine (group 17) and inert gases (group 18). A non-metal which is a liquid at room temperature is bromine (group 17).