Radioactivity of `108` undecayed radioactive nuclei of half life of `50` days is equal to that of `1.2 xx 108` number of undecayed nuclei of some material with half life of `60` days
Radioactivity is proportional to half-life.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false

Answer

C

Explanation

Radioactivity `= - (dN)/(dt)= lamda N = (0.693N)/(T_(1//2))`
`=(0.693 xx 10^(8))/(50) = (0.693 xx 1.2 xx 10^(8))/(60)`
Hence, L.H.S = R.H.S Radioactivity is proportional to `1//T_(1//2)`, and not to `T_(1//2)`