Answer
a. The impulse is the change in momentum.
Using an equation from page 93, solve for the force. Let's deal only with the magnitudes of these quantities.
$$Ft = \Delta (mv) = mv$$
$$F = \frac{mv}{t}$$
b. Using the above equation, find the average force:
$$F = \frac{mv}{t} = \frac{(1 kg)(2 m/s)}{0.2 s} =10 N$$