Question

At any instant the ratio of the amount of radioactive substances is 2 : 1. If their half lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances

• A. 1 : 1
• B. 2 : 1
• C. 1 : 2
• D. 1 : 4

Answer 1

The correct option is A 1 : 1

By using $N=N_0{\left(\frac{1}{2}\right)}^n\Rightarrow \frac{N_1}{N_2}=\frac{(N_0{)}_1}{(N_0{)}_2}\times \frac{(\frac{1}{2}{)}^{n_1}}{(\frac{1}{2}{)}^{n_2}}=\frac{2}{1}\times \frac{{\left(\frac{1}{2}\right)}^{\frac{2\times 24}{12}}}{{\left(\frac{1}{2}\right)}^{\frac{2\times 24}{16}}}=\frac{1}{1}$