Physics - Heat & Thermo Question with Solution | TestHub

Water is heated from $10{}^{\circ }\mathrm{C}$ to $90{}^{\circ }\mathrm{C}$ in a residential hot water heater at a rate of $70\mathrm{litre}$ per minute. Natural gas with a density of $1.2\mathrm{kg}$/${\mathrm{m}}^3$ is used in the heater, which has a transfer efficiency of 32%. The gas consumption rate in cubic meters per hour is: (heat of combustion for natural gas is $8400kcal/kg$):