What is energy density ? Writes its formula.

A capacitor of capacitance $C$ is charged with the help of a $200 \,V$ battery. It is then discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity $2.5 \times 10^2 \,J / kg$ and mass $0.1 \,kg$. If the temperature of the block rises by $0.4 \,K$, the value of $C$ is

A capacitor of capacitance $\mathrm{C}$ and potential $\mathrm{V}$ has energy $E$. It is connected to another capacitor of capacitance $2 \mathrm{C}$ and potential $2 \mathrm{~V}$. Then the loss of energy is $\frac{x}{3} E$, where $\mathrm{x}$ is____________.

A condenser of capacity $50\,\mu F$ is charged to $10\;volts$. Its energy is equal to

Three plates $A, B$ and $C$ each of area $0.1 \ m^2$ are separated by $0.885\  mm$ from each other as shown in the figure. $A$ $10$ $V$ battery is used to charge the system. The energy stored in the system is

A $10\,pF$ capacitor is connected to a $50 \,V$ battery. How much electrostatic energy is stored in the capacitor