Question

Assertion (A) : While moving from N to P covalent radius increases significantly but from As to Bi only a small increase is observed. 

Reason (R) : For a particular oxidation state covalent radii and ionic generally radii increases down the group. 

(1) Both (A) and (R) are correct and (R) is the correct explanation of (A) 

(2) Both (A) and (R) are correct but (R) is not the correct explanation of (A) 

(3) (A) is correct but (R) is incorrect 

(4) (A) is incorrect but (R) is correct

Answer 1

(2) Both (A) and (R) are correct but (R) is not the correct explanation of (A) 

Covalent and ionic (in a particular state) radii increases in size down the group. There is a considerable increase in covalent radius from N to P. However, from As to Bi only a small increase in covalent radii is observed. This is due to the presence of completely filled d and f-orbitals in heavier elements. (lanthanoid contraction)