At a given instant , $60 %$ of the radioactive nuclei in a sample are left undecayed. After $20$ s, $85 %$ nuclei have disintegrated, mean life of nuclei

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Answer 1

From the equation it is clear that half life if radioactive nuclei is to see,
Mean life $= \frac{1}{λ}$
   $= \frac{1}{0 . 6 9 3}$
   $= \frac{t _{1 / 2}}{0 . 6 9 3}$
   $= \frac{2 0}{0 . 6 9 3}$
$= 28.86 s$
$∴$ Mean life $= 28.86 s$ .

Answer 2

From the equation it is clear that half life if radioactive nuclei is to see,

Mean life

= \frac{1}{λ}

= \frac{1}{0 . 6 9 3}

= \frac{t _{1 / 2}}{0 . 6 9 3}

= \frac{2 0}{0 . 6 9 3}

= 28.86 s

∴

Mean life

= 28.86 s

.

At a given instant , $60 %$ of the radioactive nuclei in a sample are left undecayed. After $20$ s, $85 %$ nuclei have disintegrated, mean life of nuclei

$10$ s

$6.93$ s

$14.43$ s

$28.86$ s

From the equation it is clear that half life if radioactive nuclei is to see,
Mean life $= \frac{1}{λ}$
   $= \frac{1}{0 . 6 9 3}$
   $= \frac{t _{1 / 2}}{0 . 6 9 3}$
   $= \frac{2 0}{0 . 6 9 3}$
$= 28.86 s$
$∴$ Mean life $= 28.86 s$ .

Radioactivity of $1 0^{8}$ undecayed radioactive nuclei of half life of $50$ days is equal to that of $1.2 \times 1 0^{8}$ number of undecayed nuclei of some other material with half life of $60$ days

Radioactivity is proportional to half-life.

At a given instance, there are $90 %$ undecayed radio-active nuclei in a sample. After $20 s e c$ , there are $60 %$ of them remaining $[T a k e i n (\frac{3}{2}) = 0.4, I n 2 = 0.7 a p p r o x i m a t e l y]$ .
Match the following

There are $n$ number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, $n^{'}$ number of $β$ particles are emitted every $2 s$ , then half-life of nuclei is

There are n number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, n' number of $β$ -particles are emitted every 2 s, then half-life of nuclei is

Revise with Concepts

Discovery of Radiation

Introduction to Radioactivity

Alpha, Beta and Gamma Emission

Differentiate Between Alpha, Beta and Gamma Radiations

Background Radiations

At a given instant , 60% of the radioactive nuclei in a sample are left undecayed. After 20s, 85% nuclei have disintegrated, mean life of nuclei

10s

6.93s

14.43s

28.86s

From the equation it is clear that half life if radioactive nuclei is to see,Mean life =λ1​ =0.6931​ =0.693t1/2​​ =0.69320​ =28.86s∴ Mean life =28.86s.

Radioactivity of 108 undecayed radioactive nuclei of half life of 50 days is equal to that of 1.2×108 number of undecayed nuclei of some other material with half life of 60 days

Radioactivity is proportional to half-life.

At a given instance, there are 90% undecayed radio-active nuclei in a sample. After 20 sec, there are 60% of them remaining [Take in(23​)=0.4,In2=0.7 approximately]. Match the following

There are n number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, n′ number of β particles are emitted every 2s, then half-life of nuclei is

There are n number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, n' number of β-particles are emitted every 2 s, then half-life of nuclei is

Revise with Concepts

Discovery of Radiation

Introduction to Radioactivity

Alpha, Beta and Gamma Emission

Differentiate Between Alpha, Beta and Gamma Radiations

Background Radiations

At a given instant , $60 %$ of the radioactive nuclei in a sample are left undecayed. After $20$ s, $85 %$ nuclei have disintegrated, mean life of nuclei

$10$ s

$6.93$ s

$14.43$ s

$28.86$ s

From the equation it is clear that half life if radioactive nuclei is to see,
Mean life $= \frac{1}{λ}$
$= \frac{1}{0 . 6 9 3}$
$= \frac{t _{1 / 2}}{0 . 6 9 3}$
$= \frac{2 0}{0 . 6 9 3}$
$= 28.86 s$
$∴$ Mean life $= 28.86 s$ .

Radioactivity of $1 0^{8}$ undecayed radioactive nuclei of half life of $50$ days is equal to that of $1.2 \times 1 0^{8}$ number of undecayed nuclei of some other material with half life of $60$ days

At a given instance, there are $90 %$ undecayed radio-active nuclei in a sample. After $20 s e c$ , there are $60 %$ of them remaining $[T a k e i n (\frac{3}{2}) = 0.4, I n 2 = 0.7 a p p r o x i m a t e l y]$ .
Match the following

There are $n$ number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, $n^{'}$ number of $β$ particles are emitted every $2 s$ , then half-life of nuclei is

There are n number of radioactive nuclei in a sample that undergoes beta decay. If from the sample, n' number of $β$ -particles are emitted every 2 s, then half-life of nuclei is