Chapter 18 - Basic Electric Circuits - Learning Path Questions and Exercises - Multiple Choice Questions - Page 650: 16

(c) $T_{1}=\frac{1}{2}T_{2}$

The time constant of a RC circuit is given by $T=RC$, where R is resistance of resistor and C is the capacitance of the capacitor. In situation 1: $T_{1}=RC$ In situation 2: $T_{2}=2RC$ Thus, $T_{2}=2T_{1}$