Question

${}^{22}Ne$ nucleus, after absorbing energy, decays into two $\alpha$ -particles and an unknown nucleus. The unknown nucleus is

• A. Nitrogen
• B. Carbon
• C. Boron
• D. Oxygen

Answer 1

Answer: (B)

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
$A=22-$ ( $2\times 4$ ) $=14$
Therefore, unknown nucleus is carbon $(A=14,Z=6)$