Home
Class 12
PHYSICS
After 280 days, the activity of a radioa...

After 280 days, the activity of a radioactive sample is 6000 dps. The activity reduces to 3000 dps after another 140 days. The initial activity of the sample in dps is

A

(a) 6000

B

(b) 9000

C

(c) 3000

D

(d) 24000

Text Solution

Verified by Experts

The correct Answer is:
D
Activity reduces from 6000 dps to 3000 dps in 140 days. It implies that half-life of the radioactive sample is 140 days. In 280 days (or two half-lives) activity will remain 1/4th of the initial activity.
Hence, the initial activity of the sample is `4xx6000 dps=24000dps`
Therefore, the correct option is (d).
Promotional Banner

Topper's Solved these Questions

  • MODERN PHYSICS - 2

    DC PANDEY|Exercise Exercise 34.2|9 Videos

  • MODERN PHYSICS - 2

    DC PANDEY|Exercise Assertion And Reason|11 Videos

  • MODERN PHYSICS - 2

    DC PANDEY|Exercise Miscellaneous Examples|9 Videos

  • MODERN PHYSICS - 1

    DC PANDEY|Exercise Level 2 Subjective|23 Videos

  • NUCLEI

    DC PANDEY|Exercise C MADICAL ENTRANCES GALLERY|46 Videos

Similar Questions

Explore conceptually related problems

After 225 days the activity of a sample is 4000 decay/s. The activity reduces to 2000 decay/s after another 75 days. The initial activity of the sample is

After 300 days, the activity of a radioactive sample is 5000 dps (disintegrations per sec). The activity becomes 2500 dps after another 150 days. The initial activity of the sample in dps is

The activity of a radioactive sample is independent of

After 200 days the activity of a radioactive sample reduces to 8000 dps. After another 100 days the activity reduces to 8000/sqrt(2) dps. It can be said that:

The activity of a radioactive sample initially is 3200 dps and after 8hours activity is 100 dps. What will be the activity after 4.8hr from start in dps?

The activity of a radioactive sample is 1.6 curie, and its half-life is 2.5 days . Its activity after 10 days will be

Activity of a radioactive sample decreases to (1/3)rd of its original value in 3 days. Then, in 9 days its activity will become

A 280 day old radioactive substances shows an activity of 6000 dps, 140 days later its activity becomes 3000 dps. What was its initial activity ?