What is the resistance of a $100 \, W, 220 \, V$ bulb in $\Omega$?

Two bulbs of $40\,W$ each are connected in parallel. The total power consumed by this combination is ............. $W$.

$4$ bulbs marked $40\, W, 250\, V$ are connected in series with a $250\, V$ mains. The total power consumed is ............. $W$.

An amount of charge $Q$ passes through a coil of resistance $R$. If the current in the coil decreases to zero at a uniform rate during time $T$, then the amount of heat generated in the coil will be,

$A$ battery with a $12 \, V$ emf has an initial charge of $80 \, A \cdot h$. If the potential across the terminals stays constant until the battery is completely discharged, then this battery can deliver energy at the rate of $120 \, W$ for a time of: (in $ \, h$)

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?