Qstnid -Iv-16-the Masses Of <Sup>11</sup>c And <Sup>11</sup>b Are Respectively 11.0114 U And 11.0093 U. Find The Maximum Energy A Positron Can Have In The Β*-decay Of <Sup>11</sup>c To <Sup>11</sup>b. - 46: The Nucleus - Neet-xii-physics

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NEET-XII-Physics

46: The Nucleus

with Solutions - page 5

Qstn# iv-16 Prvs-Qstn Next-Qstn

#16
The masses of ¹¹C and ¹¹B are respectively 11.0114 u and 11.0093 u. Find the maximum energy a positron can have in the β*-decay of ¹¹C to ¹¹B.
Ans : Given:
Mass of ¹¹C, m(¹¹C) = 11.0114 u
Mass of ¹¹B, m(¹¹B) = 11.0093 u
Energy liberated in the β⁺ decay (Q) is given by
`` Q=\left[m\left({}^{11}C\right)-m\left({}^{11}B\right)-2{m}_{e}\right]{c}^{2}``
= (11.0114 u - 11.0093 u `` -`` 2`` \times ``0.0005486 u)c²
= 0.0010028 `` \times `` 931 MeV
= 0.9336 MeV = 933.6 keV
For maximum KE of the positron, energy of neutrino can be taken as zero.
∴ Maximum KE of the positron = 933.6 keV
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