NEET (UG)-2025 Chemistry code-45 Question Paper with Solutions

# Q1 of 45

The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes n = 2 → n = 3 and n = 4 → n = 6 transitions, respectively, is

Options
A.

1/36

B.

1/16

C.

1/9

D.

1/4

Show Answer
Correct Answer

1/4

Solution

The correct option is 1/4.

To find the ratio of the wavelengths of the light absorbed by a Hydrogen atom during the given transitions, we can use the Rydberg formula for the wavelength of light absorbed or emitted:
1 λ = R H 1 n 1 2 - 1 n 2 2
where:
λ is the wavelength of the light,
RH is the Rydberg constant for Hydrogen,
n1 and n2 are the principal quantum numbers of the energy levels (with n1<n2).

Step 1: Calculate the wavelength (λ1) for the transition n=2n=3
Here, n1=2 and n2=3.
Substituting these values into the Rydberg formula:
1 λ 1 = R H 1 2 2 - 1 3 2
1 λ 1 = R H 1 4 - 1 9
1 λ 1 = R H 9 - 4 36
1 λ 1 = R H 5 36
Thus, the wavelength λ1 is:
λ 1 = 36 5 R H

Step 2: Calculate the wavelength (λ2) for the transition n=4n=6
Here, n1=4 and n2=6.
Substituting these values into the Rydberg formula:
1 λ 2 = R H 1 4 2 - 1 6 2
1 λ 2 = R H 1 16 - 1 36
Taking the least common multiple of 16 and 36, which is 144:
1 λ 2 = R H 9 - 4 144
1 λ 2 = R H 5 144
Thus, the wavelength λ2 is:
λ 2 = 144 5 R H

Step 3: Find the ratio of the wavelengths (λ1/λ2)
Dividing λ1 by λ2:
λ 1 λ 2 = 36 5 R H 144 5 R H
Canceling the common factor of 5RH in the denominators:
λ 1 λ 2 = 36 144
Simplifying the fraction:
λ 1 λ 2 = 1 4

Therefore, the ratio of the wavelengths of the absorbed light is 1/4.

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