Thermodynamics relation and Avaliability

A gas having a negative Joule-Thompson  coefficient , when throttled, will

• (A) Become cooler

• (B) Become warmer

• (C) Remain at the same temperature

• (D) Either be cooler or warmer depending on the type of gas

A positive value of Joule-Thompson coefficient of a fluid means

• (A) Temperature drops during throttling

• (B) Temperature remains constant during throttling

• (C) Temperature rises during throttling

• (D) None of these

Considering the relationship Tds=dU+pdV between the entropy (S), internal energy (U), pressure (p), temperature (T) and volume (V), which of the statement is correct.

• (A) It is applicable only for a reversible process

• (B) For an irreversible process TdSdU+pdV

• (C) It is valid only for an ideal gas

• (D) It is equivalent to 1^st law, for a reversible process

A steel billet of 2000 kg mass is to be cooled from 1250 K to 450 K. The heat released during this process is to be used as a source of energy. The ambient temperature is 303 K and specific heat of steel is 0.5 kJ/kg K. The available energy of the billet is

• (A) 490.44 MJ

• (B) 30.95 MJ

• (C) 10.35 MJ

• (D) 0.10 MJ

Which combination of the following statement is correct?

P : A gas cools upon expansion only when its Joule-Thompson co-efficient is positive in the temperature range of expansion.

Q : For a system undergoing a process, its entropy remains constant only when the process is reversible.

R : The work done by a closed system in an  adiabatic process is a point function.

S : A liquid expands upon freezing when the slope of its fusion curve on pressure-temperature diagram is negative..

• (A) R and S

• (B) P and Q

• (C) Q, R and S

• (D) P, Q and R

Consider the following two processes;

 I. A heat source at 1200 K loses 2500kJ of heat to a sink at 800 K

II. A heat source at 800 K loses 2000 kJ of heat to a sink at 500 K

which of the following statement is true?

• (A) Process I is more irreversible than process II

• (B) Process II is more irreversible than  process I

• (C) Irreversibility associated in both the processes are equal

• (D) Both the process are reversible

Availability of a system at any state is given as

The maximum theoretical work when system interact to surrounding is called as

Joule Thomson coff. for ideal gas is

• 1

• 0

• less than 0

• more than 0

The symbol of Helmholtz free energy is_________

• a) A

• b) H

• c) B

• d) E