The correct option is D 4
As per the question, for H atom
rn+1−rn=rn−1 ...(i)
where rn=Radius of Bohr's nth energy level
As per Bohr's theory, rn=0.529n2Z
For H atom, rn=0.529 n2
Similiarly, rn+1=0.529(n+1)2
rn−1=0.529(n−1)2
Putting these values in equation (i), we get
0.529(n+1)2−0.529 n2=0.529(n−1)2
⇒(n+1)2−n2=(n−1)2
⇒n2−4n=0
⇒n(n−4)=0
⇒n=0 or n=4
Since n=0 is not possible, the only possible value is n=4.