NEET Questions Solved


If ΔQ and ΔW represent the heat supplied to the system and the work done on the system respectively, then the first law of thermodynamics can be written as 

(1) ΔQ = ΔU + ΔW

(2) ΔQ = ΔU – ΔW

(3) ΔQ = ΔW – ΔU

(4) ΔQ = –ΔU – ΔW

where ΔU is the internal energy

(2) From FLOT ΔQ=ΔU+ΔW

∵ Heat supplied to the system so ΔQ → Positive

and work is done on the system so ΔW → Negative

Hence +ΔQ = ΔU – ΔW

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