NCERT Class XII Chapter
Nuclei
Questions With Solutions
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Question : 26
Total: 31
Under certain circumstances, a nucleus can decay by emitting a particle more massive than an α-particle. Consider the following decay processes:
R a
P b +
C
R a
R n +
H e
Calculate the Q-values for these decays and determine that both are energetically allowed
Calculate the Q-values for these decays and determine that both are energetically allowed
Solution:
Let us calculate Q value for the given decay process.
For first decay process
Q = m(
R a ) − m (
P b ) − m (
C )
Q = [223.01850 – 208.98107 – 14.00324] (c 2
= [0.034109] × 931.5 MeV = 31.85 MeV
For the second decay process
Q = m(
R a ) − m (
R n ) − m (
H e )
Q = [223.01850 – 219.00948 – 4.00260]c 2
Q = 0.00642 × 931.5 MeV = 5.98 MeV
Since, Q value is positive in both the cases, hence decay process in both ways are possible.
For first decay process
Q = m
Q = [223.01850 – 208.98107 – 14.00324] (
= [0.034109] × 931.5 MeV = 31.85 MeV
For the second decay process
Q = m
Q = [223.01850 – 219.00948 – 4.00260]
Q = 0.00642 × 931.5 MeV = 5.98 MeV
Since, Q value is positive in both the cases, hence decay process in both ways are possible.
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