Question

how much work is done in moving a charge of 2 coulomb from a point at 118 volt to a point at 128 volt ??

Answer 1

work W= V*Q [ volt into coulomb]
for 118 volt 
W = V*Q
    = 118 * 2
    =236 joule
for 128
W = V*Q
    = 128 * 2
    = 256 joule
work done for 118v to 128v is = 256 - 236
                                            = 20 joule

Answer 2

W/q=V
work done per unit test charge is known as potential.
W=q(V2-V1)
V1=potential of initial point
V2=potential of final point
q=charge which is moving from one potential to another potential
W=2(128-118)
W=2x10=20 CV=20joule