The different isotopes have different "half-lives" – the time it takes to lose half of its radioactivity. Pu-239 has a half-life of 24,100 years and Pu-241's half-life is 14.4 years. Substances with shorter half-lives decay more quickly than those with longer half-lives, so they emit more energetic radioactivity.
Montresor deserves to be penalised in court with the sentencing of 1st degree murder. Montresor was not insane, he was a pervasive murderer because of his motive.
