What is the commercial unit of electric energy?

$(i)$ Draw a circuit diagram to show how two resistors are connected in series.
$(ii)$ In a circuit,if two resistors of $5 \ \Omega$ and $10 \ \Omega$ are connected in series,how does the current passing through the two resistors compare?

Which has a greater resistance$-$a $100$ $W$ bulb or a $60$ $W$ bulb?

Define one watt hour.

$A$ nichrome wire has a resistance of $10\, \Omega$. Find the resistance of another nichrome wire,whose length is three times and area of cross-section four times the first wire.

What is the formula to find electric power $P$?