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When electromagnetic radiation of wavelength 300 ~nm falls on the surface of a metal, electrons are emitted with the kinetic energy of 1.68 × 10^5 J…

NEET UG 2022 — Chemistry Physical Chemistry

2022mcqmedium

When electromagnetic radiation of wavelength 300 nm300 \mathrm{~nm}300 nm falls on the surface of a metal, electrons are emitted with the kinetic energy of 1.68×1051.68 \times 10^51.68×105 Jmol−1\mathrm{J} \mathrm{mol}^{-1}Jmol−1. What is the minimum energy needed to remove an electron from the metal? (h=6.626×10−34Js,c=3×108 ms−1,NA=6.022×1023 mol−1\begin{aligned} & \left(h=6.626 \times 10^{-34} \mathrm{Js}, \mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1},\right. \\ & \mathrm{N}_{\mathrm{A}}=6.022 \times 10^{23} \mathrm{~mol}^{-1} \end{aligned}​(h=6.626×10−34Js,c=3×108 ms−1,NA​=6.022×1023 mol−1​

Official previous-year question

Held on 30 Apr 2022 · Verified 9 Jul 2026.

Options

  1. A

    2.31×106 J mol−12.31 \times 10^6 \mathrm{~J} \mathrm{~mol}^{-1}2.31×106 J mol−1

  2. B

    3.84×104 J mol−13.84 \times 10^4 \mathrm{~J} \mathrm{~mol}^{-1}3.84×104 J mol−1

  3. C

    3.84×10−19 J mol−13.84 \times 10^{-19} \mathrm{~J} \mathrm{~mol}^{-1}3.84×10−19 J mol−1

  4. D

    2.31×105 J mol−12.31 \times 10^5 \mathrm{~J} \mathrm{~mol}^{-1}2.31×105 J mol−1

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