Question

Covalent radius of nitrogen is 70 pm, the covalent radius of boron is about
(A) 60
(B) 110
(C) 50
(D) 40

Answer 1

Hint: Covalent radius is known as half of the distance between the nuclei of two covalently bonded atoms in a homo diatomic molecule which is called the covalent radius. The trends observed in a periodic table within a period are to be identified. Based on the aforesaid relations the covalent radius of boron is to be derived.

Complete step by step answer:
The covalent radius is known as half of the distance between the nuclei of two covalently bonded atoms in a homo diatomic molecule. The elements given to us are boron and nitrogen which belong to the same period.
We know that elements are arranged following the atomic numbers in the periodic table. On moving from left to right in a period, the atomic number increases. By observing this we can say that the atomic number of boron is less than nitrogen.
Like the following trend other properties like a decrease in the atomic radius. Now as we move from left to right in a period the radius starts decreasing and simultaneously down the group it increases.
Therefore the relation between the radii among the given elements are as follows
$B(Z = 5) > N(Z = 7)$
So the radius should be greater than 70 pm as along a period it is inversely proportional to the atomic number.
So the covalent radius of boron is 110 pm.

So, the correct answer is Option B.

Note: The energy level increases as we move down the group as the number of electrons increases. Each next level is far from the last level. Hence the atomic radius increases down the group.