Section A
Q1 I discounted B and D as there's just not enough info to work these out... Not C, as the time constant isn't time to halve, but time to fall to 37%.
So it must be A, as using 0.1ms=RC gives the capacitance as 1E-7F, which is 10μF.
Q2 ? I have no idea, brain is feeling fried...
Q3 B? as F=BQV, F=2 x 1.6E-19 x 1.6E7, F=5.12E-12 N
So we disagree on this one...
Q4 C? as E=F/Q and E=V/d,
so F/Q=V/d
so Fd=VQ, as work done=Forcexdistance,
150E-6 = 30E-6 x V
so V= 150/30 = 5V
I will do the last question later too, having a break now though... Back in 1 hour!