Two bulbs of equal wattage, one having carbon filament and the other having a tungsten filament, are connected in series to the mains. Then which of the following is a correct observation?

Carbon filament bulb glows more.

Here, carbon filament bulb and the tungsten filament bulb, are connected in series, hence current through them is same.

Therefore, Q = I²Rt

⇒Q∝R

Also, carbon is non-metal (semiconductor) and tungsten is metal (conductor) hence, the resistance of carbon filament is more than tungsten filament.

Hence, carbon filament bulb glows more than tungsten filament bulb.