AI Mentor

Check Your IQ

Free Expert Demo

Try Test

Courses

Dropper NEET Course Dropper JEE Course Class - 12 NEET Course Class - 12 JEE Course Class - 11 NEET Course Class - 11 JEE Course Class - 10 Foundation NEET Course Class - 10 Foundation JEE Course Class - 10 CBSE Course Class - 9 Foundation NEET Course Class - 9 Foundation JEE Course Class -9 CBSE Course Class - 8 CBSE Course Class - 7 CBSE Course Class - 6 CBSE Course

Offline Centres

The half life of a radio active substance is 10 days. This means that

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

The substance completely disintegrates in 20 days.

1/8 part of the total number of active nuclei of the substance will be left infact at the end of 40 days.

The substance completely disintegrates in 40 days.

7/8 th part of the total number of active nuclei of the substance disintegrates in 30 days.

answer is D.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

After 30 days (i.e. 3 half lives) number of active nuclei left is given by $N = \frac{N_{0}}{{(2)}^{\frac{3 T}{3}}} = \frac{N_{0}}{8}$ .

So total number of nuclei disintegrates in 30 days $= N_{0} - \frac{N_{0}}{8} = \frac{7}{8} N_{0}$

Watch 3-min video & get full concept clarity

courses

No courses found

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Online Course for IIT JEE

Best Online Course for NEET

Best Online Course for CBSE

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Get Expert Academic Guidance – Connect with a Counselor Today!