2. Questions Bank
  3. JEE Main & Advanced
  4. Chemistry
  5. Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन

JEE Main & Advanced Chemistry Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन Question Bank Rate of decay and Half-life

  • question_answer
    \[8gm\] of the radioactive isotope, cesium-137 were collected on February 1 and kept in a sealed tube. On July 1, it was found that only \[0.25gm\] of it remained. So the half-life period of the isotope is            [KCET 1989]

    A)                 37.5 days            

    B)                 30 days

    C)                 25 days

    D)                 50 days

    Correct Answer: B

    Solution :

           \[t\] = Feb 1 to July 1 =\[28+31+30+31+30=150\text{ days}\]                    \[\lambda =\frac{2.303}{150}\log \frac{8}{0.25}=\frac{2.303}{150}\log {{2}^{5}}\]\[=\frac{0.693}{30}\text{da}{{\text{y}}^{-1}}\]                                 \[{{t}_{1/2}}=\frac{0.693}{0.693/30}=30\,\text{days}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner