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

Which of the following is not equal to watt?

There are four bulbs of power $100 \,W, 200 \,W, 500 \,W$ and $1000 \,W$. Among these, which filament has the highest resistance? (Assuming the same voltage source)

$A$ wire of resistance $R$ is connected across a cell of emf $\varepsilon$ and internal resistance $r$. The current through the circuit is $I$. In time $t$,the work done by the battery to establish the current $I$ is

$A$ $25\, W$,$220\, V$ bulb and a $100\, W$,$220\, V$ bulb are connected in parallel across a $220\, V$ line. Which bulb will glow more brightly?

By what percentage will the illumination of the lamp decrease if the current drops by $20 \%$ (in $\%$)?