Question

The half-life of hydrogen-3 (tritium) is approximately 12 years. In how many years will half of a 20-gram sample decay by beta radiation to helium-3?

6
12
10
20

Answer 1

The definition of half life is the amount of time it takes for half the material to decay. It doesn't matter how much material you start with or the mode by which it decays. In 12 years, half of the hydrogen-3 atoms will become helium-3. The answer is 12.

Answer 2

Half of a 20-gram sample decay by beta radiation to helium-3 (tritium ) is 12 years - half-life of tritium.

◆HALF LIFE of a material is the time taken for half the material to decay.

It doesn't matter by whatever means it decayed.

◆ Here, time taken to decay half of 20 gm tritium by beta radiation is required. Which is same as the half life of of tritium.

◆It doesn't matter by what means of by what amount it should be reduced , Reducing 1kg to 500g and 20g to 10g takes equal time to equal radiation.