The bulb of one thermometer is spherical while that of other is cylindrical. Both have equal amounts of mercury, which one will respond quickly to temperature?

. The thermometer having cylindrical bulb will respond fastly to the temperature. For same volume a sphere has least surface area.
The surface area of cylindrical bulb will be more than that of the spherical bulb. More heat will be transmitted to mercury through cylindrical bulb surface. It will respond quickly to the temperature.