1.

Radioactiv edecay will occur as follows overset(220)86Rnrarroverset(216)84PO + overset(4)2He Half life =55s overset(216)84Porarroverset(212)82Pb + overset(4)2He Half life =0.66s overset(812)82Pbrarroverset(212)82BL + gamma^(@)(4)e Half life =10.6 h If a certain mass of radon (Rn=220) is allowed to decay in a certain container,then after 5 minutes the element with the greater mass will be

Answer»

radon
polonium
lead
bismuth

Solution :Let `M_(0)` be intial mass of RN-220 Number of half lives of Rn in 5 munuites `=(5MIN)/(55s)=(5xx60)/(55)=5.5`
`therefore Mass of Rn-220(left)=(1)/(2)^(5.5) M_(0)=(M_(0)/(45)`
`therefore The mass converted in to Po-216 is `(44//45)`
`M_(0)` Number of hlf lives of Po-216 in 5 minutes
`=(5min)/(0.66)=(300)/(0.66)=455`
`therefore Mass of Po-216left=((1)/(2))^(455)xx(44)/(45)M_(0)rarr0`
This means that Po-216 formed will soon decay to lead HENCE lead will havemaximum mass NEARLY `(44)/(45)M_(0)`


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