Millikan measured the quantity of charge carried
by an electron. how did he then calculate the
mass of an electron?

m = E × Q

And Q = I × t

m = E × I × t

Where m = mass in grams

Q = quantity of electricity in coulomb

I = current in ampere

t = time in seconds

E = electrochemical equivalent of the substance

Explanation:

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

14 days is the half-life of phosphorus-32