A geyser heats water flowing.at the rate of 3.0 L/min from 27°C to 77°C. If the geyser operates on a gas . burner, what is the rate of combustion of the fuel if its heat of combustion is 4.0 x ${{10}^{4}}$ J/g?

Here, volume of water heated = 3.0 L/min

Mass of water heated, m = 3000 g/min

Rise in temperature, ∆T = 77 - 27 = 50°C

Specific heat of water, C = 4.2 J${{g}^{-1}}$ ${{C}^{-1}}$

Amount of heat used,

∆Q = mc∆T = 3000 x 4.2 x 50 = 63 x ${{10}^{4}}$ J / min

Heat of combustion = 4 x ${{10}^{4}}$ J/g

Rate of combustion of fuel = 63 x ${{10}^{4}}$ / 4 x ${{10}^{4}}$ = 15.75 g/min