A capacitor c is connected in series with a resistor r across a battery and an open switch. if a second capacitor of capacitance 2c is connected in parallel with the first one, the time constant of the new rc circuit will be

Okay it would be really heplful if there was a figure present, now its not clear that where the capacitor (2C) is connected? is it parallel with the R+C combination or just with C?

still im going to assume that 2C is being connected with C in parallel

so