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QPages 442-444: Q42: HC Verma: Concepts of Physics - Volume 2 The Nucleus Pages 442-444: Q42 Solution: can disintegrate either by emitting an -particle of by emitting …
can disintegrate either by emitting an -particle of by emitting a -particle. a) Write the two equations showing the products of the decays. b) The probabilities of disintegration - and -decays are in the ratio 7/13. The overall half-life of is one hour. If 1 g of pure is taken at 12.00 noon, what will be the composition of this sample at 1 P.m. the same day?
Step-by-Step Verified Solution
**Answer:** (a) _-decay: ___Bi _ ___Tl + _; __-decay: ___Bi _ ___Po + e_ + __. (b) Composition: 0.35 g Bi, 0.65 g Po/Tl mixture.
**Step-by-Step Explanation:**
(a) ___Bi (Z=83) can undergo:
- _-decay: ___Bi _ ___Tl (Z=81) + _He.
- __-decay: ___Bi _ ___Po (Z=84) + e_ + __.
(b) Half-life = 1 h. After 1 h, half the nuclei decay.
Probability of _-decay = 7/20, _-decay = 13/20.
Mass of Bi remaining = 0.5 g.
Mass of Tl (from _-decay) = 0.5 _ (7/20) _ (208/212) = 0.172 g.
Mass of Po (from _-decay) = 0.5 _ (13/20) _ (212/212) = 0.325 g.
Composition: 0.5 g Bi, 0.172 g Tl, 0.325 g Po[citation:2].
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