UPSEE Solved Model Paper 1

In time t1′ radioactive material decays 1/9 part
⇒ 8/9 past remains.
In time t2 radioactive material decays 8/9 past
⇒ 1/9 part remains
𝐴𝑡 𝑡 = 𝑡1 , 𝑁1 = 8𝑁O/9
𝐴𝑡 𝑡 = 𝑡2, 𝑁2 = 𝑁𝑂/9

N2

N1

=

1

8

= (

1

2

)3
N2 = (

1

2

)3N1
So, (t2−t1) - t1∕2×3
= 3t1∕2