Q.

As per given figure A, B and C are the first, second and third excited energy level of hydrogen atom respectively. If the ratio of the two wavelengths (i.e., λ1λ2) is 74n, then the value of n will be _______.                [2023]


Ans.

(5)

As    1λ=RZ2[1n12-1n22]

1λ1=R(1)2[1(2)2-1(3)2]=R(536)    (i)

1λ2=R(1)2[1(3)2-1(4)2]=R(7144)    (ii)

(ii) + (i) gives

λ1λ2=7144536=720=74×5

 n=5