Spontaneity

Q. A sample of 1.0 mol of a monoatomic ideal gas is taken through a cyclic process of explanation and compression as shown in fig. What will be the value of $△H$ for the cycle as a whole?

Q. When one mole of an ideal gas at 30 atm pressure and 12 L volume expands such that the final pressure becomes 15 atm and the final volume becomes 48 L. Calculate entropy change for the process. [Given that C_p = 29.1 J mol^–1 K^–1, R = 8.314 J mol^–1 K^–1 and log 2 = 0.3]

जब 30 atm दाब पर तथा 12 L आयतन वाली एक मोल आदर्श गैस इस प्रकार प्रसारित होती है कि अंतिम दाब 15 atm तथा अंतिम आयतन 48 L हो जाता है। प्रक्रम के लिए एन्ट्रॉपी परिवर्तन की गणना कीजिए। [दिया गया है कि C_p = 29.1 J mol^–1 K^–1, R = 8.314 J mol^–1 K^–1 तथा log 2 = 0.3]

1. 32.45 J mol^–1 K^–1
   
2. 67.35 J mol^–1 K^–1
   
3. 25.85 J mol^–1 K^–1
   
4. 73.26 J mol^–1 K^–1
   

Q. More than One Answer Type
एक से अधिक उत्तर प्रकार के प्रश्न

Two moles of an ideal monoatomic gas undergoes cyclic process as shown in below figure. Select the correct statement(s) about the processes.

दो मोल एकलपरमाणुक आदर्श गैस नीचे चित्र में दर्शाए अनुसार चक्रीय प्रक्रम से गुजरती है। प्रक्रम के विषय में सही कथन/कथनों का चयन कीजिए।

1. A to B is isothermal process
   
   A से B तक समतापीय प्रक्रम है
2. B to C is reversible adiabatic process
   
   B से C तक उत्क्रमणीय रूद्धोष्म प्रक्रम है
3. C to D is isoenthalpic process
   
   C से D तक समएन्थैल्पीय प्रक्रम है
4. D to A is reversible adiabatic compression
   
   D से A तक उत्क्रमणीय रूद्धोष्म संपीडन है

Q. Identify the correct statements regarding entropy

1. At $0^{o}C,$ the entropy of a perfectly crystalline substance is taken to be zero
2. At absolute zero of temperature, the entropy of all perfectly crystalline substance is positive
3. At absolute zero of temperature, the entropy of all crystalline substance is taken to be negative
4. At absolute zero of temperature, the entropy of a perfectly crystalline substance is taken to be zero

Q. The enthalpy change for a given reaction at 298 K is $-xJmo{l}^{-1}$ (x being positive). If the reaction occurs spontaneously at 298 K, the entropy change at that temperature

1. can be negative but numerically larger than $\frac{x}{298}$
2. can be negative but numerically smaller than $\frac{x}{298}$
3. cannot be negative
4. cannot be positive

Q.

A spontaneous process has to be instantaneous.

1. True

2. False