A small bottle contains powered beryllium Be & gaseous radon which is used as a source of `alpha`-particles. Netrons are produced when `alpha-`particles of the radon react with beryllium. The yield of this reaction is `(1//4000)` i.e. only one `alpha`-particle out of induced the reaction. Find the amount of radon `(Rn^(222))` originally introduced into the source, if it prouduces `1.2 xx 10^(6)` neutrons per second after `7.6` days. [`T_(1//2)` of `R_(n) = 3.8` days]

Answer

`3.3 xx 10(-6) g`