Question

determine both the mass and the charge of a block of material consisting of 3 x 10 ^27 protons,3 x10^37 neutrons, and 3.1 x 10^27 electrons

Answer 1

The mass:

$$m=N_pm_m+N_nm_n+N_em_e\\ =3*10^{27}*1.67*10^{-27}+3*10^{37}*1.67*10^{-27}\\ +3.1*10^{27}*9.1*10^{-31}=5.01*10^{10}\:\rm kg$$

The caharge:

$$q=N_pq_m+N_eq_e\\ =3*10^{27}*1.6*10^{-19} -3.1*10^{27}*1.6*10^{-19}\\ =-1.6*10^{7}\:\rm C$$