Question Details

The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be :

Options

A

1/2

B

1/(2√2)

C

2/3

D

2/(3√2)

Show Answer

Correct Answer :

Option B

1/(2√2)

1/(2√2)

Solution :

The correct option is 1/(2√2).

To find the fraction of the original radioactive activity that remains after a certain amount of time, we can use the radioactive decay formula based on the number of half-lives. The formula is:


NN0=(12)n

Where:

- N is the final amount of activity remaining.
- N0 is the initial amount of activity.
- n is the number of half-lives that have elapsed.

First, we calculate the number of half-lives (n) by dividing the total time elapsed (t) by the half-life (T1/2):


n=tT1/2=150100=32

Now, substitute n=32 into the decay formula to find the fraction remaining:


NN0=(12)32

We can simplify this exponential expression step-by-step:


(12)32=13/223/2=123/2

A fractional exponent of 3/2 is equivalent to cubing the number and taking the square root:


123/2=123

Since 23=8, we have:


18

Finally, we can simplify the radical by factoring out a perfect square (8=4·2), taking the square root of 4 out of the radical:


18=122

Thus, the fraction of the original activity that will remain is 122.

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