Q: 22Ne nucleus, after absorbing energy, decays into two α-particles and an unknown nucleus. The unknown nucleus is
(A) nitrogen
(B) carbon
(C) boron
(D) oxygen
Ans: (B)
Sol: Atomic number of Neon = 10
By the emission of alpha particle , atomic number will be decreases by 2 units & mass number decreases by 4 units.
Hence , Atomic number of unknown element = 10 – 4 = 6
And , Mass number of unknown element = 22 – 8 = 14
Hence , unknown element is Carbon (A= 14 , Z = 6)