JEE Main 2015PhysicsNuclear PhysicsMediumMCQ

JEE Main 2015 — Nuclear Physics Question with Solution

JEE Main 2015 (11 Apr Online)

Question

Let Nβ be the number of β particle emitted by 1 gram of Na24 radioactive nuclei having a half life of 15 h. In 7.5 h, the number Nβ is close to NA=6.023×1023 mole-1

Choose an option

Show full solutionCorrect option: C
Correct answer
C7.5×1021

Step-by-step explanation

∵NN0=12n
N = no. of un-decayed nuclei
N0 = initial no. of nuclei
Also t=n×T12
⇒NN0=12tT12
⇒N=N0127.515
⇒N=N01212⇒N=N02 
∴ Number of nuclei decayed
=N0-N02=N02-12
=0.4141.414N0
=0.29N0
∵N0=124×6.023×1023
⇒ No. of nuclei decayed =0.29×124×6.023×1023
=0.0727×1023
=7.5×1021

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About this question

This is a previous-year question from JEE Main 2015, covering the Nuclear Physics chapter of Physics. 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.