A gas is cooled and loses 65J of heat. The gas contracts as it cools and the work done on the system is equal to 20J. What is △U?
A
−45J
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
B
−65J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
+45J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
−20J
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution
The correct option is A−45J From the first law of thermodynamics, △U=Q+W where, Q is the heat transfer and W is the work done in the process. Q=−65J,W=20J △U=−65+20=−45J