﻿ The half-life of  is 28 years. How much is the disintegration rate of 15 mg of this isotope? The Avogadro’s number is . : Kaysons Education

# The Half-life Of  is 28 Years. How Much Is The Disintegration Rate Of 15 Mg Of This Isotope? The Avogadro’s Number is .

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## Question

### Solution

Correct option is

1 gram-atom of  has a mass of 90 g and contains  atoms. Therefore, the number of atoms in 1 g of , and that in 15 mg  is

The half-life T of  is 28 years. Therefore, its decay constant is

The rate of disintegration, when N atoms are present, is given by

.

Substituting the above values of  and N, we get

.

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