Question

0. The radius of first Bohr orbit in hydrogen atom is ro, then the radius of first orbit in helium atom will (A) 2r0 (B) 4r0 (C) r0/2 (D) ro ​

Answer 1

answer: r0/2

Explanation

Radius of nth orbit in any atom rn=0.529/z

if atom = z=1 and r1=r0

thus, r0= 0.529

z=2

radius of first orbit in helium r1=0.529/2

=r0/2