How many calories of heat will be produced approximately in a $210\, W$ electric bulb in $5$ minutes?

If the power in the external resistance $R$ is maximum,then which of the following statements are correct?
$(i) R = r$
$(ii)$ Power in $R$ is $\frac{E^2}{4R}$
$(iii)$ Input power is $\frac{E^2}{2R}$
$(iv)$ Efficiency is $50\%$

$n$ identical bulbs,each designed to consume power $P$ at a certain voltage source,are connected in series across the same source. The total power consumed by them is:

The power dissipated by a uniform wire of resistance $100 \Omega$ when a potential difference of $120 \text{ V}$ is applied across its ends is (in $W$)

The energy dissipated by a resistor is $10 \, mJ$ in $1 \, s$ when an electric current of $2 \, mA$ flows through it. The resistance is $....... \, \Omega$ (Round off to the Nearest Integer).

Two heating coils of resistances $10 \Omega$ and $20 \Omega$ are connected in parallel and connected to a battery of emf $12 \text{ V}$ and internal resistance $1 \Omega$. The ratio of the power consumed by them is: