0000000 Two heat-insulating pistons connected by a spring can slide without friction inside a horizontal heat insulating tube, which is open at both of its ends. One mole of a mono-atomic gas is filled between the pistons at temperature T = 300 K. At this temperature of the gas, the spring is not relaxed. If an amount of heat is supplied to the gas, its temperature becomes T = 400 K and length of the spring becomes 77= 1.1 times of its initial length. How much heat is supplied to the gas?