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PhysicsModern PhysicsRadioactivityEasy2 minPYQ_2020

PhysicsEasysingle choice

A sample contains $10^{- 2} kg$ each of the two substances $A$ and $B$ with half-lives $4 s$ and $8 s$ respectively. Their atomic weights are in the ratio of $1 : 2$ . Amounts of $A$ and $B$ after an interval $16 s$ are

Options:

Answer:

Solution:

The amount left after $N$ half - lives

$N = N_{0} {[\frac{1}{2}]}^{n}$

For A,

$n = \frac{t}{T_{\frac{1}{2}}} = \frac{16 s}{4 s} = 4$

$N_{A} = 10^{- 2} kg {[\frac{1}{2}]}^{4} = 6.25 \times 10^{- 4} kg$

For B,

$n = \frac{16 s}{8 s} = 2$

$N_{B} = 10^{- 2} kg {[\frac{1}{2}]}^{2} = 2.5 \times 10^{- 3} kg$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:Modern PhysicsSubtopic:Radioactivity

⏱ 2mℹ️ Source: PYQ_2020

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