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Physics · PYQ NEET UG 2019(2)
हिन्दीThe rate of radioactive disintegration at an instant for a radioactive sample of half-life \( 2.2 \times 10^9 \text{ s} \) is \( 10^{10} \text{ s}^{-1} \). The number of radioactive atoms in that sample at that instant is,
Correct answer · Option A
\( 3.17 \times 10^{19} \)
Explanation
Activity \( -\frac{dN}{dt} = \lambda N \). Here \( \lambda = \frac{\ln 2}{T_{1/2}} = \frac{0.693}{2.2 \times 10^9} \text{ s}^{-1} \). Then \( N = \frac{10^{10}}{\lambda} \approx 3.17 \times 10^{19} \).
