Combination of Capacitors question from JEE Main 2022 (26 Jun, Shift 2)

Answer: (a)

1. Series: $\frac{1}{C} = \frac{1}{10} + \frac{1}{15} + \frac{1}{20} = \frac{6+4+3}{60} = \frac{13}{60}$, so $C = \frac{60}{13}\ \mu\text{F}$.
2. $Q = CV = \frac{60}{13}\times 13 = 60\ \mu\text{C}$
3. In series every capacitor has the same charge, so the $15\ \mu\text{F}$ has $60\ \mu\text{C}$.
4. So the answer is (a) 60$\mu$C.