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Physics Question 2 – NEET-UG 2024

Match List I with List II. List IList II(Spectral Lines of Hydrogen for(Wavelengths (nm))transitions from)A.n2=3 to n1=2I. 410.2B. n2=4 to n1=2II. 434.1C. n2=5 to n1=2III. 656.3D. n2=6 to n1=2IV. 486.1 Choose the correct answer from the options given below :

The spectral lines of hydrogen are governed by transitions of electrons between different energy levels.

Step 1: Apply Rydberg Formula for Balmer Series✦ Active

The transitions are all to n1=2, which corresponds to the Balmer series. The Rydberg formula for the wavelength λ of spectral lines in hydrogen is given by:

1λ=RH(1n12−1n22)

Where RH=1.097×107 m−1 is the Rydberg constant. We will calculate λ for each transition.

💡 Teacher's Secret Hint

Remember that n2 must always be greater than n1 for emission spectra.

Step 2: Calculate Wavelengths for Each Transition○ Expand

A) For n2=3 to n1=2:

1λA=RH(122−132)=RH(14−19)=RH(9−436)=5RH36 λA=365RH=365×1.097×107 m−1≈6.563×10−7 m=656.3 nm

B) For n2=4 to n1=2:

1λB=RH(122−142)=RH(14−116)=RH(4−116)=3RH16 λB=163RH=163×1.097×107 m−1≈4.861×10−7 m=486.1 nm

C) For n2=5 to n1=2:

1λC=RH(122−152)=RH(14−125)=RH(25−4100)=21RH100 λC=10021RH=10021×1.097×107 m−1≈4.341×10−7 m=434.1 nm

D) For n2=6 to n1=2:

1λD=RH(122−162)=RH(14−136)=RH(9−136)=8RH36=2RH9 λD=92RH=92×1.097×107 m−1≈4.102×10−7 m=410.2 nm
💡 Teacher's Secret Hint

The wavelengths calculated correspond to the visible region of the electromagnetic spectrum, characteristic of the Balmer series.

Step 3: Match Transitions to Wavelengths○ Expand

Based on the calculations:

A) n2=3 to n1=2 corresponds to 656.3 nm (List II - III).

B) n2=4 to n1=2 corresponds to 486.1 nm (List II - IV).

C) n2=5 to n1=2 corresponds to 434.1 nm (List II - II).

D) n2=6 to n1=2 corresponds to 410.2 nm (List II - I).

Thus, the correct matching is A-III, B-IV, C-II, D-I. This matches option (1).

💡 Teacher's Secret Hint

As n2 increases, the energy difference between levels decreases, leading to shorter wavelengths (higher frequencies).

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