How long would it take to accumulate a charge of 460 mC using a current of 0.2 A?

Your answer can be derived from an understanding of the
unit of current. In your problem, 0.2 A of current is flowing. (We'll assume that this
value remains unchanged for the duration of the experiment. In practice this is rarely
the case when one is speaking of accumulated current, for example in a
capacitor.)

The unit of current is the Ampere (A, or Amp).
The definition of the Ampere is 1 C / s (1 Coulomb/second). So, to get the amount of
charge that has traveled past a specific point (or accumulated), multiply the current by
the time:

Charge ( in Coulombs) = Coulombs / second x
#seconds

Or, for your problem
statement,

460 mC = 460 x10-3 Coulombs = 0.2 Coulombs /
second x  T seconds

Solve for
T:

T = 0.460 C / 0.2 A = 2.3 seconds