Question

A radioactive substance has a constant activity of $2000$ disintegrations per minute. The material is separated into two fractions, one of which has an initial activity of $1000$ disintegrations per second while the other fraction decays with $t_{1/2}=24$ hours. The total activity in both samples after $48$ hours of separation is:

• A. $1500$
• B. $1000$
• C. $1250$
• D. $2000$

Answer 1

The correct option is D $2000$

First fraction

$Ao=100$ dps

Second fraction $t1/2=24$ hrs

Since radiation sample and has $\alpha$ has a constant activity of $2000$ dps. So it will remain same after $48$ hrs also.