## Question

### Solution

Correct option is

12 h

The radioactivity of a sample decreases to  in n half lives. Since the initial activity is 64 times the permissible level, it must become  of its initial value.

In other words in six half-lives the activity will reduce itself to the permissible level. Since half life is 2 hours, the total time taken

= 12 hours.

#### SIMILAR QUESTIONS

Q1

How much energy is released when one amu is wholly converted into energy?

Q2

In the equation

,

The correct symbol for X is

Q3

The kinetic energy of a 300 K thermal neutron is

Q4

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Q5

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Q6

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Q7

After two hours  of the initial amount of a certain radioactive isotope remains undecayed. The half life of the isotope is

Q8

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Q9

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Q10

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