A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 3.0 per minute. The half life of the source is

Question

A count rate meter shows a count of 240 per minute from a given radioactive source- One hour later the meter shows a count rate of 30 per minute- The half life of the is-20 min120 min80 min30 min

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Since in radioactive decay- the decay rate is proportional to the amount of substance-xA0-Hence-xA0-2402N-30- where N is number of half lives passed in one hour-xA0-This gives- N-3-xA0-Hence half life- t1-2-603min-20-xA0-min

A count rate meter shows a count of $240$ per minute from a given radioactive source. One hour later the meter shows a count rate of $30$ per minute. The half life of the source is:
$20 m i n$
$120 m i n$
$80 m i n$
$30 m i n$

Since in radioactive decay, the decay rate is proportional to the amount of substance.
Hence, $\frac{240}{2^{N}} = 30$ , where N is number of half lives passed in one hour.
This gives, $N = 3$ .
Hence half life: $t_{1 / 2} = \frac{60}{3} m i n = 20 m i n$

A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half life of the source is:20 min120 min80 min30 min

Since in radioactive decay, the decay rate is proportional to the amount of substance. Hence, 2402N=30, where N is number of half lives passed in one hour. This gives, N=3. Hence half life: t1/2=603min=20 min

A count rate meter shows a count of $240$ per minute from a given radioactive source. One hour later the meter shows a count rate of $30$ per minute. The half life of the source is:
$20 m i n$
$120 m i n$
$80 m i n$
$30 m i n$

Since in radioactive decay, the decay rate is proportional to the amount of substance.
Hence, $\frac{240}{2^{N}} = 30$ , where N is number of half lives passed in one hour.
This gives, $N = 3$ .
Hence half life: $t_{1 / 2} = \frac{60}{3} m i n = 20 m i n$