JEE Main 2021ChemistryChemistry in Everyday LifeMediumNumerical

JEE Main 2021 — Chemistry in Everyday Life Question with Solution

JEE Main 2021 (26 Aug Shift 2)

Question

A metal surface is exposed to 500 nm radiation. The threshold frequency of the metal for photoelectric current is 4.3×1014 Hz. The velocity of ejected electron is ___×105 ms-1 (Nearest integer)
Use:h=6.63×10-34Js,me=9.0×10-31 kg

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Show full solutionCorrect answer: 5
Correct answer
5

Step-by-step explanation

λ=500 nm→v=Cλ=3×108500×10-9=6×1014 Hz

v0=4.3×1014 Hz

For photo electric effect, hv=hv0+KE

KE=hv-hv0=hv-v0=6.6×10-346×1014-4.3×1014

=6.6×1.7×10-20 J

 K.E. =12mv2;v=2×K·Em

V=2×6.6×1.7×10-209.1×10-31=24.65×1010=5×105 m/s

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About this question

This is a previous-year question from JEE Main 2021, covering the Chemistry in Everyday Life chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.