Answer
A has 3 electrons
B has 6 electrons
C has 4 electrons
D has 8 electrons
Work Step by Step
Since each drop must contain an integral (or whole) number of electrons, the charge of each drop must be a whole-number multiple of the electron’s charge. By this logic, the maximum charge whose multiples are found in the drops is $-1.6 \times 10^{-9}$ z.
The charge on the electron = $-1.6 \times 10^{-9}$ z.
Hence,
number of electrons in drop A = 3
number of electrons in drop B = 6
number of electrons in drop C = 4
number of electrons in drop D = 8
