Q.

The radius of electron’s second stationary orbit in Bohr’s atom is R. The radius of 3rd orbit will be          [2023]

1 R3  
2 2.25 R  
3 3 R  
4 9 R  

Ans.

(2)

rn2Z

r2ndr3rd=(n2n3)2

Rr3rd=(23)2

r3rd=94R=2.25R