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:

  1. 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 ( $A=14, Z=6$ ).



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