CBSE Class 12 · 2003 · Modern PhysicsShort Answer

Explain with an example whether the neutron-proton ratio in a nucleus increases or decreases due to beta (

β

) decay.

Answer: It decreases (a neutron becomes a proton).

Solution

β^{-}

decay a neutron converts into a proton:

n \to p + e^{-} + \overset{ν}{ˉ}

.
So the number of neutrons falls by one and the number of protons rises by one; the ratio

N / Z

decreases.
Example:

_{6}^{14} C \to_{7}^{14} N + e^{-} + \overset{ν}{ˉ}

, where

N / Z

changes from

8/6 = 1.33

7/7 = 1.0

N / Z decreases

CBSE Class 12 Board · 2003 · Subjective