$(i)$ Calculate the number of electrons which will together weigh $1 \, g$.
$(ii)$ Calculate the mass and charge of one mole of electrons.

$(i)$ Mass of one electron $= 9.10939 \times 10^{-31} \, kg$.
Number of electrons that weigh $9.10939 \times 10^{-31} \, kg = 1$.
Number of electrons that will weigh $1 \, g$ $(1 \times 10^{-3} \, kg)$:
$= \frac{1 \times 10^{-3} \, kg}{9.10939 \times 10^{-31} \, kg} = 0.1098 \times 10^{28} = 1.098 \times 10^{27}$ electrons.
$(ii)$ Mass of one electron $= 9.10939 \times 10^{-31} \, kg$.
Mass of one mole of electrons $= (6.022 \times 10^{23}) \times (9.10939 \times 10^{-31} \, kg) = 5.48 \times 10^{-7} \, kg$.
Charge on one electron $= 1.6022 \times 10^{-19} \, C$.
Charge on one mole of electrons $= (1.6022 \times 10^{-19} \, C) \times (6.022 \times 10^{23}) = 9.65 \times 10^{4} \, C$.