in need of help Watch
(a) Calculate the time from the moment of connecting the relay coil across the 12V dc. supply for the capacitor to charge to 6V.
Secondly, the way the forum works is that we help you to do the question yourself.
In order that we can do this you need to tell us what it is you don't understand. What theory have you done for this and what equations do you know?
For a start, do you know the exponential formula for charging/discharging a capacitor?