Question bank/JEE Main/Physics

The activity of a radioactive sample falls from
[IMAGE] to [IMAGE] in 30 minutes. Its
half life is close to

A62 minB66 minC72 minD52 min

Show answer and solution▾

$\Rightarrow \text{\quad}\frac{ln2}{ln(7/5)} = \frac{t_{\frac{1}{2}}}{(30\min)} \Rightarrow \text{\quad}(2.06004)30 = t_{\frac{1}{2}} = 61.8\text{min}$

Source: Grass-G / P-15 Physics paper 11 Nov.docx