Is electric potential and capacitance class 12 a hard chapter?

It is the farad (F). The name came from Michael Faraday. SI Unit of Capacitance means the ability of a system to store an electric charge. One farad is the capacitance of a device that needs one coulomb of charge to provide one volt potential difference across it. Mathematically, it is represented by - 1 Farad = 1 Coulomb/Volt. 

In JEE Main Physics, electric potential and capacitance chapter has a weightage of 3% to 6%. You can expect around 1 or 2 questions from this chapter which carries 4 to 8 marks.

In NEET Physics exam, the chapter electric potential and capacitance carries a weightage of 2% to 5%, which means you can expect one question out of 45 questions.

The ability to do work on a charge is called the electric potential and the ability to store charge is termed as the capacitance.

After switch ‘S’ is closed

$Q_1+Q_2=C_{1}V$ -    (1)

              Using KVL

              $\frac{Q_1}{C_1}-\frac{Q_2}{C_2}=0$  

              $Q_1=Q_2\frac{C_1}{C_2}$                       - (2)

              from (1) & (2)

              $\Rightarrow Q_2\left[\frac{C_1+C_2}{C_2}\right]=C_{1}V\Rightarrow Q_2=\left(\frac{C_1{C}_2}{C_1+C_2}\right)V$