Which of the following cannot be emitted by radioactive substances during their decay ?

Options

A. Protons
B. Neutrinos
C. Helium nuclei
D. Electrons

Answer

C

Explanation

If N is the number of radioactive nuclei present at some instant, then
`N=N_(0)e^(-lamdat)`
The constant `N_(0)` represents are number of radioactive nuclei at t=0
Now, `(N_(1))/(N_(2))=(e^(-lamda_(1)t))/(e^(-lamda_(2)t))=(e^(-5lamdat))/(e^(-lamdat))=e^(-4lamdat)`
but `(N_(1))/(N_(2))=(1)/(e)` (as provided)
Therefore, `(1)/(e)=(1)/(4^(4lamdat))`
or `4lamdat=1`
or `t=(1)/(4lamda)`