Three samples of a radioactive substance have activity in a ratio 2 : 5 : 7 , then after two half lives the ratio of their activities will be:

The percentage of radioactive substance left after 5 half lives is

At certain time, the activity of three radioactive materials are in the ratio of 3 : 4 : 5 . What will be the mark ratio of their activities at any further date?

The number of nuclei of two radioactive substance is the same and their half-lives are 1 year and 2 years respectively. The ratio of their activities after 6 years will be

The number of nuclei of two radioactive substance is the same and their half-lives are 1 year and 2 years respectively. The ratio of their activities after 6 years will be

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

Two samples of different radioactive substances initially have the ratio of active nuclei 4 : 1 and then half lives are 12 hr. and 16 hr. respectively. Find the ratio of active nuclei of the two samples after 2 days.

At any instant, the ratio of the amount of radioactive substance 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 sample of radioactive substance loses half of its activity in 4 days. The time in which its activity is reduced to 5% is

A sample of radioactive substance loses half of its activity in 4 days. The time in which its activity is reduced to 5% is

A sample contains two radioactive substances A and B in the ratio of 4 : 1 . If their half lives are 24 and 16 hours respectively , then after two days what will be the ratio of A and B?