JEE Main 2024 · 5 April · evening · Single correct · +4 / −1
Match List I with List II :
Choose the correct answer from the options given below :
| LIST I EM-Wave | LIST II Wavelength Range | ||
|---|---|---|---|
| A. | Infra-red | I. | <10⁻³ nm |
| B. | Ultraviolet | II. | 400 nm to 1 nm |
| C. | X-rays | III. | 1 mm to 700 nm |
| D. | Gamma rays | IV. | 1 nm to 10⁻³ nm |
- (a) (A)-(I), (B)-(III), (C)-(II), (D)-(IV)
- (b) (A)-(III), (B)-(II), (C)-(IV), (D)-(I)
- (c) (A)-(IV), (B)-(III), (C)-(II), (D)-(I)
- (d) (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
Answer and solution
Answer (b) (A)-(III), (B)-(II), (C)-(IV), (D)-(I)
Solution
Physics sir · 3 steps
Line the four waves up from longest to shortest wavelength, and the four ranges fall into place.
- Order the waves. Going from long to short wavelength, the order is infra-red, then visible light, then ultraviolet, then X-rays, then gamma rays. Visible light sits between about 700 nm and 400 nm, and that is the anchor.
- Order the ranges. Sort List II the same way: 1 mm to 700 nm is the longest, then 400 nm to 1 nm, then 1 nm to 10⁻³ nm, and finally less than 10⁻³ nm.
Wave Where it sits Range Match Infra-red just longer than red light (700 nm) 1 mm to 700 nm (A)-(III) Ultraviolet just shorter than violet light (400 nm) 400 nm to 1 nm (B)-(II) X-rays shorter than UV 1 nm to 10⁻³ nm (C)-(IV) Gamma rays shortest of all < 10⁻³ nm (D)-(I) - So. The matching is (A)-(III), (B)-(II), (C)-(IV), (D)-(I), which is option (b).
The idea to keep. Remember visible light as 400 to 700 nm. Infra-red is just beyond red, ultraviolet is just beyond violet, and X-rays and then gamma rays keep getting shorter.
Answer from the NTA final answer key. Solution by PrepWiser.