Half-life of radioactive substance is 3.20 h . What is the time taken for 75% of substance to be used?

Correct answer: A. 6.4 h N _ 0 → _ 1 N _ 0 2 → _ 2 N _ o 4 Remaining substance after two half lives is N _ 0 4 (or) the substance used during this time = N _ 0 - N _ 0 4 = 3 N _ 0 4 = 75% N _ 0

NTA Abhyas 2020

Exam: NTA Abhyas
Year: 2020
Subject: Physics
Chapter: Nuclear Physics

NTA Abhyas 2020 · Physics · Nuclear Physics

Half-life of radioactive substance is 3.20 h . What is the time...

Half-life of radioactive substance is

\text{3}\text{.20 h}

. What is the time taken for

\text{75%}

of substance to be used?

Options

A $\text{6}\text{.4 h}$
B $\text{12 h}$
C $\text{4}\text{.18}$ day
D $\text{1}\text{.2}$ day

Correct answer

A. $\text{6}\text{.4 h}$

Step-by-step solution

{N}_{0}\mathop{→}_{1}\dfrac{{N}_{0}}{2}\mathop{→}_{2}\dfrac{{N}_{o}}{4}

Remaining substance after two half lives is

\dfrac{{N}_{0}}{4}

(or)

the substance used during this time

= {N}_{0} - \dfrac{{N}_{0}}{4} = 3\dfrac{{N}_{0}}{4} = 75%{N}_{0}

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