In a test of a water-jacketed compressor, the shaft work required is 90 kN\[\,-\,\]m/kg of air compressed. During compression, increase in enthalpy of air is 30 kJ/kg of air and increase in enthalpy of circulating cooling water is 40 kJ/kg of air. The change in velocity is negligible. The amount of heat lost to the atmosphere from the compressor per kg of air is:

• A. 20 kJ
• B. 60 kJ
• C. 80 kJ
• D. 120 kJ