At time `t=0`, some radioactive gas is injected into a sealed vessel. At time `T`, some more of the same gas is injected into the same vessel. Which one of the following graphs best represents the variation of the logarithm of the activity `A` of the gas with time `t`?

Options

A.
B.
C.
D.

Answer

B

Explanation

`A=A_(0)e^(-lambdat)`
`l n A= l n A_(0)-lambdat`
`l n A` versus `t` is a linearly decreasing graph with slope depending to `lambda`. As `lambda` does not change, slope remains same.