(b) $Q_{1} = \frac{C_{1}}{C_{1} + C_{2}}Q_{n}\ \ \ \ \&\ \ \ Q_{2} = \frac{C_{2}}{C_{1} + C_{2}}Q_{n}$ $\Rightarrow Q_{1} = \frac{6c}{6c + 3c} \times 9q\ \ \ \&\ \Rightarrow Q_{2} = \frac{3c}{6c + 3c} \times 9q$ $= 6q\ \ \ \ \ \&\ = 3q$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.