can disintegrate either by emitting an α-particle or by emitting a β–-particle.
(a) Write the two equations showing the products of the decays.
(b) The probabilities of disintegration by α-and β-decays are in the ratio 7/13. The overall half-life of 212Bi is one hour. If 1g of pure 212Bi is taken at 12.00 noon, what will be the composition of this sample at 1 p.m. the same day?
(a) 21283Bi
20881Ti + 
21283Bi
21284Bi + 
-
(b) t1/2= 1h
After 1h, 21283Bi will be half decayed
So, 21283Bi is 0.5g present
20881Ti and 21284Bi will be formed in the ratio 7/13 and total mass of the sample should be 1g. So, total mass of 20881Ti and 21284Bi is 0.5g.
⇒ Mass of 20881Ti will be ratio of mass present × total mass= 
And mass of 21284Bi will be of mass present × total mass= 