I need help with these two resistancecapacitator problems Pl

I need help with these two resistance/capacitator problems. Please help. I\'m terrible at this stuff.

Q1) A variable resistor, R, is connected to the terminals of a battery (dashed box in the diagram). The graph below shows data collected in the circuit as R is varied.  

A) What is V₀, in volts?

B) What is the internal resistance, r, in ohms?

Q2) Which of the following statements are correct for the RC circuit shown (with brief explanation)?

After S is moved to b, it takes a time ? = RC, for the charge on C to drop to 1/e of its initial value.

After S is in the position b for a long time, the current through R becomes close to zero.

The longer S is kept in the position a, the lower is the energy stored in C.

If S is in the position a for a long time, the current through R approaches ?/R.

If S is in the position a for a long time, the charge on C approaches zero.

Right after S is moved to the position a, following a long time in the position b, the current through R is ?/R.

Right after S is moved to the position b, following a long time in the position a, the current through R is zero.

Solution

1)

I=Vo/(R+r)

to solve for Vo,

Vo=I(R+r) got two equations

Vo=0.9(r)

*since when R=0, I=0.9

Then i used another point

Vo=0.2(18+r)

so compare these two equations

r = 5.142 ohm

and

Vo = 4.63 v

2)

If S is in the position a for a long time, the current through R approaches /R.