What is the value of $1 \, kWh$ in Joules?

How much heat (in $cal$) is produced when a $210 \, W$ bulb is kept on for $5 \, min$? (Given $J = 4.2 \, J/cal$)

An electrical cable having a resistance of $0.2 \Omega$ delivers $10 \text{ kW}$ at $200 \text{ V}$ $D$.$C$. to a factory. What is the efficiency of transmission (in $\%$)?

The battery of a mobile phone is rated as $4.2 \ V, 5800 \ mAh$. How much energy is stored in it when fully charged (in $kJ$)?

An electric heater heats a certain amount of water in $5 \, \text{min}$ when connected to a $220 \, \text{V}$ supply. How many minutes will it take to heat the same amount of water when connected to a $110 \, \text{V}$ supply?

Power generated across a uniform wire connected across a supply is $H$. If the wire is cut into $n$ equal parts and all the parts are connected in parallel across the same supply,the total power generated in the wire is