Question

The half life of ${}^{226}\text{Ra}$ is $1602$ year. Calculate the activity of $0.1$ $g$ of $RaC{l}_2$ assuming all the $Ra$ atoms are ${}^{226}\text{Ra}$ and mass of $Cl$ atom is $35.5$ $g/mol$

• A. $1.8\times {10}^8$ $dps$
• B. $2.8\times {10}^8$ $dps$
• C. $1.8\times {10}^9$ $dps$
• D. $2.8\times {10}^9$ $dps$

Answer 1

The correct option is D $2.8\times {10}^9$ $dps$

Number of ${}^{226}\text{Ra}$ atoms present $=\frac{0.1}{297}\times 6.02\times {10}^{23}$
Activity $=\lambda N=$ $\frac{0.693}{0.602\times 3.156\times {10}^7}\times \frac{1}{297}6.02\times {10}^{22}$$=2.8\times {10}^9$ $dps$