Assertion : If half life of a radioactive substance is 40, days then 25% substance decay in 20, days

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13.Nuclei

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Assertion : If the half life of a radioactive substance is $40\, days$ then $25\%$ substance decay in $20\, days$

Reason : $N = {N_0}\,{\left( {\frac{1}{2}} \right)^n}$

where, $n = \frac{{{\rm{time\, elapsed}}}}{{{\rm{half \,life \,period}}}}$

If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.

If the Assertion is correct but Reason is incorrect.

If the Assertion is incorrect but the Reason is correct

(AIIMS-1998)

Solution

Half life of radioactive substance is $40\, days$. It means $50\%$ substance decays in $40\, days$. During this period rate of decay is on decrease. So, $25\%$ decay must have taken place is less than $20\, days$.

$N = {N_0}\,{\left( {\frac{1}{2}} \right)^n}$ , where $n = \frac{{{\rm{time\, elapsed}}}}{{{\rm{half \,life\, period}}}}$

Standard 12

Physics

Write the definition and unit of decay constant.

easy

A radioactive sample has ${N_0}$ active atoms at $t = 0$. If the rate of disintegration at any time is $R$ and the number of atoms is $N$, then the ratio $ R/N$ varies with time as

medium

Two radioactive substances $A$ and $B$ have decay constants $5\lambda $ and $\lambda $ respectively. At $t = 0$, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become $(\frac {1}{e})^2$ will be

medium

(JEE MAIN-2019)

At time $t=0$, a container has $N_{0}$ radioactive atoms with a decay constant $\lambda$. In addition, $c$ numbers of atoms of the same type are being added to the container per unit time. How many atoms of this type are there at $t=T$ ?

normal

(KVPY-2010)

Curie is a unit of

easy

(AIPMT-1989)

Assertion : If the half life of a radioactive substance is $40\, days$ then $25\%$ substance decay in $20\, days$ Reason : $N = {N_0}\,{\left( {\frac{1}{2}} \right)^n}$ where, $n = \frac{{{\rm{time\, elapsed}}}}{{{\rm{half \,life \,period}}}}$

Solution

Similar Questions

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Assertion : If the half life of a radioactive substance is $40\, days$ then $25\%$ substance decay in $20\, days$

Reason : $N = {N_0}\,{\left( {\frac{1}{2}} \right)^n}$

where, $n = \frac{{{\rm{time\, elapsed}}}}{{{\rm{half \,life \,period}}}}$