A geyser heats water flowing at a rate of 2.0 kg per minute from 30$$^\circ$$C to 70$$^\circ$$C. If geyser operates on a gas burner, the rate of combustion of fuel will be ___________ g min^$$-$$1.

[Heat of combustion = 8 $$\times$$ 10³ Jg^$$-$$1, Specific heat of water = 4.2 Jg^$$-$$1 $$^\circ$$C^$$-$$1]

A heat engine operates with the cold reservoir at temperature 324 K. The minimum temperature of the hot reservoir, if the heat engine takes 300 J heat from the hot reservoir and delivers 180 J heat to the cold reservoir per cycle, is ____________ K.

When a gas filled in a closed vessel is heated by raising the temperature by 1$$^\circ$$C, its pressure increases by 0.4%. The initial temperature of the gas is ___________ K.

A steam engine intakes 50 g of steam at 100$$^\circ$$C per minute and cools it down to 20$$^\circ$$C. If latent heat of vaporization of steam is 540 cal g^$$-$$1, then the heat rejected by the steam engine per minute is __________ $$\times$$ 10³ cal.

(Given : specific heat capacity of water : 1 cal g^$$-$$1 $$^\circ$$C^$$-$$1)