Modern Physics 7 Question 36
37. ${ }^{22} Ne$ nucleus, after absorbing energy, decays into two $\alpha$-particles and an unknown nucleus. The unknown nucleus is
$(1999,2 M)$
(a) nitrogen
(b) carbon
(c) boron
(d) oxygen
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Solution:
- Atomic number of neon is 10 . By the emission of two $\alpha$-particles, atomic number will be reduced by 4 . Therefore, atomic number of the unknown element will be $Z=10-4=6$
Similarly, mass number of the unknown element will be
$$ A=22-2 \times 4=14 $$
Unknown nucleus is carbon ( $A=14, Z=6$ ).
