[单选题]
A certain amount of a monatomic gas is maintaine kl (nwm41ji)sd at constant volu.e 2lngimo(. n7hlx,tme as it is cooled by 50 K. This feat is accomplished by removing 400 J of energy from the gas. How much work is do7tnn.ox .lhm,2gile( ne by the gas?
