### Q.1:- A geyser heats water flowing at the rate of 3.0 litres per minute from 27 °C to 77 °C. If the geyser operates on a gas burner, what is the rate of consumption of the fuel if its heat of combustion is 4.0 × 10^{4} J/g?

**Answer:-**

Water is flowing at a rate of 3.0 litre/min.

The geyser heats the water, raising the temperature from 27°C to 77°C.

Initial temperature, *T*_{1} = 27°C

Final temperature, *T*_{2} = 77°C

∴Rise in temperature, Δ*T* = *T*_{2} – *T*_{1}

= 77 – 27 = 50°C

Heat of combustion = 4 × 10^{4} J/g

Specific heat of water,* c *= 4.2 J g^{–1 }°C^{–1}

Mass of flowing water, *m* = 3.0 litre/min = 3000 g/min

Total heat used, Δ*Q* = *mc* Δ*T*

= 3000 × 4.2 × 50

= 6.3 × 10^{5 }J/min

∴ Rate of consumption = 6.3 × 10^{5} / (4 × 10^{4}) = 15.75 g/min.