713 N,613C{ }_{7}^{13} \mathrm{~N},{ }_{6}^{13} \mathrm{C}713 N,613C
1840Ar,2040Ca{ }_{18}^{40} \mathrm{Ar},{ }_{20}^{40} \mathrm{Ca}1840Ar,2040Ca
2040Ca,1940 K{ }_{20}^{40} \mathrm{Ca},{ }_{19}^{40} \mathrm{~K}2040Ca,1940 K
1531P,1632 S{ }_{15}^{31} \mathrm{P},{ }_{16}^{32} \mathrm{~S}1531P,1632 S