Question

The following statements concern elements in the periodic table. Which of the following is true?
A.) For group $15$ elements the stability of $+ 5$ oxidation state increases down the group
B.) Elements of group $16$ have lower ionisation energy values compared to those of group $15$ in the corresponding periods.
C.) The group $13$ elements are all metals.
D.) All the elements in group $17$ are gases.

Answer 1

The group $15$ elements half filled electronic configuration due to which the ionisation energy values of group $15$ is more than the ionisation energy values for group $16$. It is difficult to remove an electron from group $15$ elements.

Complete step by step answer:
The group $- 15$ elements are also called the nitrogen family. They have general electronic configuration as $n{s^2}n{p^3}$. This group can exhibit $+ 3, - 3, + 5$ oxidation states. It can acquire $+ 5$ oxidation state by losing three $np$ electrons and two $ns$ electrons. When we go from top to bottom in group$- 15$, the stability of $+ 5$ oxidation state decreases from phosphorus to bismuth.
Hence, Option A.) is an incorrect option.
In this question, by ionisation energy we mean that energy which is required to remove an electron from the outermost shell of an isolated gaseous atom.
The group $-16$ elements have general electronic configuration as $n{s^2}n{p^4}$ and also we know that group-$15$ elements have general electronic configuration in which the outer $p -$shell is half filled. So, it has half filled electronic configuration. Due to this half-filled configuration, group $- 15$ has extra stability which makes the removal of electrons very difficult from it. Thus, the energy required to remove an electron from group$- 15$ is high. Hence, the ionisation energy of group $- 15$ elements is higher than that of group $- 16$.
Hence, Option B.) is the correct option.
The elements of group $- 13$ are known as the boron family in which boron is a typical non metal and other compounds are metallic in nature.
Hence, option C.) is incorrect.
The elements of group $17$ are known halogens in which only fluorine and chlorine are gases at room temperature.
Hence, option D.) is incorrect.
Therefore, Option B is the correct answer.

Note:
Remember that the oxidation state is referred to the degree of oxidation, that is, it describes the number of loss of electrons. If oxidation state is positive then it means that the element is losing electrons and if it is negative then the element is gaining electrons.