Cans with compressed air are often used to clean computer keyboards or other ele
ID: 1837041 • Letter: C
Question
Cans with compressed air are often used to clean computer keyboards or other electronic components. When the can is operated it gets very cold to the touch. This is because the associated thermodynamic process is: a. Isobaric b. Isochoric; c. Isothermal; d. Adiabatic. An event happens in which a system's entropy increases by 10 J/K, while the entropy of the surroundings decreases by 8 J/K. The process is: a. Reversible; b. Irreversible; c. Impossible. An inventor claims to have constructed a heat engine that operates between 300 K and 1000 K with an efficiency of 40 %. This heat engine violates: a. The first law of thermodynamics; b. The second law of thermodynamics; c. The third law of thermodynamics; d. None of the laws of thermodynamics.Explanation / Answer
30
Compressed air causes the container to be cold and this process known as adibatic expansion
Therefore correct option is (d).
31.
Total entropy of the system is 10 J/K-8.0J/K=2.0 J/K,which is positive or (>0) and this process is
knwon as irreversible process.
Therefore correct option is (b).
32.
Efficiency of the heat engine operated between temperature limits is,
n=1-T2/T1
= 1-300 K/1000K
=07 or 70% which is more than cornot heat engine efficiency(40%)
This violtes second law of thermodynaamics.
Therefore correct option s (b)