Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • Engineering
  • BITSAT The half-life of a certain radioactive element is T. How long will it take for 75% of a sample of the element to decay?

  1. 2T

  2. T

  3. 3/2T

  4. 3T

Answers (1)

Radioactive decay, N(t) = N_{0} e^{- \frac{0.693t}{t_{1/2}}}

Where N(t) is the amount of sample which remains after time t.

Given that 75% of the sample has decayed, hence the remaining will be 25% of initial, N(t) =0.25 N_{0}

Also t_{1/2} =T

0.25 N_{0} =N_{0}e^{- \frac{0.693t}{T}}

\Rightarrow 0.25 =e^{- \frac{0.693t}{T}}

Take loge both sides and solve

t = 2T

Option (1) is correct

Posted by

Abhishek Sahu

View full answer

Similar Questions

Trending Articles/News

anam-khan

BITSAT 2025 preference editing window open till July 5 for BE, BPharm, MSc admission
anam-khan

BITSAT cut-off for BE Computer Science slightly drops, increases for all others; session 2 result soon
anam-khan

BITSAT 2025 edit window to modify choices, preferences opens tomorrow; iteration-1 result on July 9

Latest Question