A change in state involving a decrease in entropy can be spontaneous, only if
(A) It is exothermic
(B) It is isenthalpic
(C) It takes place isothermally
(D) It takes place at constant volume

1 Answer

Answer :

(A) It is exothermic

Related questions

Description : Change in internal energy in a closed system is equal to heat transferred if the reversible process takes place at constant  (a) pressure  (b) temperature  (c) volume  (d) internal energy  (e) entropy.

Last Answer : Answer : c

Description : Change in enthalpy in a closed system is equal to heat transferred if the reversible process takes place at constant  (a) pressure  (b) temperature  (c) volume  (d) internal energy  (e) entropy.

Last Answer : Answer : a

Description : Pick out the wrong statement: (A) The expansion of a gas in vacuum is an irreversible process (B) An isometric process is a constant pressure process (C) Entropy change for a reversible adiabatic process is zero (D) Free energy change for a spontaneous process is negative

Last Answer : (B) An isometric process is a constant pressure process

Description : Pick out the wrong statement. (A) The conversion for a gas phase reaction increases with decrease in pressure, if there is an increase in volume accompanying the reaction (B) With ... phase reaction increases with increase in pressure, if there is a decrease in volume accompanying the reaction

Last Answer : (B) With increase in temperature, the equilibrium constant increases for an exothermic reaction

Description : For a spontaneous process, free energy (A) Is zero (B) Increases (C) Decreases whereas the entropy increases (D) And entropy both decrease

Last Answer : C) Decreases whereas the entropy increases

Description : For spontaneous changes in an isolated system (S = entropy) (A) ds = 0 (B) ds 0 (D) ds = Constant

Last Answer : (C) ds > 0

Description : Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the ... isolated system (D) At absolute zero temperature, the heat capacity for many pure crystalline substances is zero

Last Answer : (C) There is an increase in entropy, when a spontaneous change occurs in an isolated system

Description : An ideal gas is heated at constant volume and then expanded isothermally. Show processes on P-V & T-S diagrams.

Last Answer : Process 1-2 : Constant volume process Process 2-3 : Constant temperature process (Isothermal process)

Description : Pick out the wrong statement. (A) Surface tension of a substance vanishes at critical point, as there is no distinction between liquid and vapour phases at its critical point (B) Entropy of ... is negative for exothermic reactions (D) The eccentric factor for all materials is always more than one

Last Answer : (D) The eccentric factor for all materials is always more than one

Description : Spontaneous change is one in there is: (1) A lowering of entropy (2) A lowering of free energy (3) Increase in free energy (4) An increase in Internal energy

Last Answer : (2) A lowering of free energy Explanation: Entropy and enthalpy together make a new quantity, the Free Energy which, under conditions of constant temperature and pressure, determines the direction of spontaneous change. All spontaneous processes have a negative change in free energy.

Description : Spontaneous change is one in there is: (1) A lowering of entropy (2) A lowering of free energy (3) Increase in free energy (4) An increase in Internal energy

Last Answer : A lowering of free energy

Description : In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is (A) More (B) Less (C) Same (D) Unpredictable; depends on the particular reaction

Last Answer : (C) Same

Description : Melting of ice exemplifies a/an (A) Adiabatic process (B) Endothermic reaction (C) Exothermic reaction (D) Process involving a chemical reaction

Last Answer : (B) Endothermic reaction

Description : On the pressure-enthalpy diagram, condensation and de-superheating is represented by a horizontal line because theprocess (a) takes place at constant pressure (b) takes place at constant temperature (c) takes place at constant entropy (d) takes place at constant enthalpy

Last Answer : Ans: a

Description : Joule-Thomson experiment is (A) Isobaric (B) Adiabatic (C) Isenthalpic (D) Both (B) & (C)

Last Answer : (D) Both (B) & (C)

Description : In thermodynamics, a throttling process, also called a _________, is a type of isenthalpic process where a liquid or gas is cooled as it passes from a higher pressure state to a lower pressure state.  a. Rankine Process  b. Carnot Cycle  c. Joule-Thomson process  d. Refrigeration process

Last Answer : Joule-Thomson process

Description : During which of following process does heat rejection take place in Carnot vapour cycle? [IES-1992] (a) Constant volume (b) constant pressure (c) Constant temperature (d) constant entropy

Last Answer : (c) Constant temperature

Description : When vapour is compressed isothermally the ____________ changes. A] Volume. B] Pressure C] Temperature D] None of the mentioned

Last Answer : A] Volume.

Description : Assertion :- Entropy of system increases for a spontaneous reactions. Reason :- Enthalpy of reaction always decreases for spontaneous reaction.

Last Answer : Assertion :- Entropy of system increases for a spontaneous reactions. Reason :- Enthalpy of reaction ... D. If both Assertion & Reason are false.

Description : Assertion (A): May endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperature. Reason (R ) : Entropy of

Last Answer : Assertion (A): May endothermic reactions that are not spontaneous at room temperature become spontaneous ... . If both Assertion & Reason are false.

Description : In a spontaneous irreversible process the total entropy of the system and surroundings

Last Answer : In a spontaneous irreversible process the total entropy of the system and surroundings A. Remains constant B. Increases C. Decreases D. Zero

Description : Change in enthalpy of a system is the heat supplied at  (a) constant pressure  (b) constant temperature  (c) constant volume  (d) constant entropy  (e) N.T.P. condition.

Last Answer : Answer : a

Description : During photosynthesis, energy is absorbed by chlorophyll, therefore it is: (a) exothermic reaction (b) endothermic reaction (c) neither exothermic nor endothermic reaction (d) the process takes place in plants only

Last Answer : (b) endothermic reaction

Description : An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ reactor feed temperature. (A) Is always equal to (B) Is always greater than (C) Is always less than (D) May be greater or less than

Last Answer : (B) Is always greater than

Description : Pick out the correct statement. (A) A chemical reaction accompanied by absorption of heat is called an exothermic reaction (B) A chemical reaction accompanied by evolution of heat is called an ... does not change on changing the concentration units (D) Chemical equilibrium state is dynamic in nature

Last Answer : (C) The rate constant for a first order reaction does not change on changing the concentration units

Description : Isobaric process means a constant process. (A) Temperature (B) Pressure (C) Volume (D) Entropy

Last Answer : (B) Pressure

Description : Superheating of steam is done at constant (A) Enthalpy (B) Entropy (C) Pressure (D) Volume

Last Answer : Option C

Description : Carnot cycle is also termed as the constant __________ cycle in thermodynamics. (A) Entropy (B) Pressure (C) Volume (D) Heat

Last Answer : Option D

Description : The first order gas phase reaction as shown in the bellow figure is conducted isothermally in batch mode. The rate of change of conversion with time is given by (A) dXA /dt = k1 (1 - XA ) 2 (1 + 2XA ) (B) dXA /dt = k1 (1 - XA ... 5XA ) (C) dXA /dt = k1 (1 - XA ) (D) dXA /dt = k1 (1 - XA )/(1 + XA )

Last Answer : (C) dXA /dt = k1 (1 - XA

Description : Melting of wax is accompanied with __________ in entropy. (A) Increase (B) Decrease (C) No change (D) None of these

Last Answer : (A) Increase

Description : The air standard Otto cycle comprises a two constant pressure processes and two constant volume processes b two constant pressure and two constant entropy processes c. two constant volume processes and two constant entropy processes d. none of the above.

Last Answer : ANSWER (c) two constant volume processes and two constant entropy processes

Description : What are the names given to constant temperature, constant pressure, constant volume, constant internal energy, constant enthalpy, and constant entropy processes.

Last Answer : Isothermal, isochroic, isobaric, free expression, throttling and adiabatic processes respectively.

Description : What is the energy absorbed during chemical reaction under constant volume conditions?  A. Entropy  B. Ion exchange  C. Enthalpy  D. Enthalpy of reaction

Last Answer : Enthalpy

Description : If value of n is infinitely large in a polytropic process pV” = C, then the process is known as constant  (a) volume  (b) pressure  (c) temperature  (d) enthalpy  (e) entropy

Last Answer : Answer : a

Description : Which of the following parameters is constant for a mole for most of the gases at a given temperature and pressure  (a) enthalpy  (b) volume  (c) mass  (d) entropy  (e) specific volume.

Last Answer : Answer : b

Description : An ideal gas is compresses isothermally. The enthalpy change is  a. Always negative  b. Always positive  c. zero  d. undefined

Last Answer : zero

Description : The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions. (A) Autocatalytic (B) Exothermic (C) Endothermic (D) Autothermal

Last Answer : (A) Autocatalytic

Description : Pick out the correct statement. (A) Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero (B) Melting of ice involves increase in enthalpy and ... of an ideal gas depends only on its pressure (D) Maximum work is done under reversible conditions

Last Answer : (D) Maximum work is done under reversible conditions

Description : ω-oxidation takes place by the hydroxylase in microsomes involving (A) Cytochrome b (B) Cytochrome c (C) Cytochrome p-4500(D) Cytochrome a3

Last Answer : Answer : C

Description : . The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is (A) R loge 4 (B) R log10 4 (C) Cv log10 4 (D) Cv loge 4

Last Answer : (A) R loge 4

Description : . The entropy change in a reversible isothermal process, when an ideal gas expands to four times its initial volume is (A) R loge 4 (B) R log10 4 (C) Cv log10 4 (D) Cv loge 4

Last Answer : (A) R loge 4

Description : The expression for entropy change given by, ΔS = - nR ln (P2/P1), holds good for (A) Expansion of a real gas (B) Reversible isothermal volume change (C) Heating of an ideal gas (D) Cooling of a real gas

Last Answer : (B) Reversible isothermal volume change

Description : The expression for entropy change given by, ΔS = nR ln (V2/V1) + nCvln (T2/T1) is valid for (A) Reversible isothermal volume change (B) Heating of a substance (C) Cooling of a substance (D) Simultaneous heating and expansion of an ideal gas

Last Answer : (D) Simultaneous heating and expansion of an ideal gas

Description : The following gas phase reactions are carried out isothermally in a CSTR. A → 2R ; r1 = k1pA ; k1 = 20mole/(sec.m3 bar) A → 3S ; r2 = k2 pA ; k2 = 40mole/(sec.m3 .bar) What is the maximum possible value of FR(mole/sec.)? (A) 1/3 (B) 1/2 (C) 2/3 (D) 2

Last Answer : (C) 2/3

Description : In a turbine, the fluid expands almost (A) Isothermally (B) Isobarically (C) Adiabatically (D) None of these

Last Answer : (C) Adiabatically

Description : A gas performs the maximum work, when it expands (A) Non-uniformly (B) Adiabatically (C) Isobarically (D) Isothermally

Last Answer : (C) Isobarically

Description : One mole of nitrogen at 8 bar and 600 K is contained in a piston cylinder arrangement. It is brought to 1 bar isothermally against a resisting pressure of 1 bar. The work done (in Joules) by the gas is (A) 30554 (B) 10373 (C) 4988.4 (D) 4364.9

Last Answer : (B) 10373

Description : When ice cubes are made, the entropy of water – (1) does not change (2) decreases (3) increases (4) may either increase or decrease depending on the process used

Last Answer : (2) decreases Explanation: When water is frozen into ice, the temperature drops below 0°C. Since the entropy of the solid is less than that of the liquid, the entropy of the water (the system ... decrease is found by dividing the heat of fusion of ice by the temperature for the reversible pathway.

Description : When ice cubes are made, the entropy of water (1) does not change (2) decreases (3) increases (4) may either increase or decrease depending on the process used

Last Answer : decreases

Description : Specific __________ does not change during phase change at constant temperature and pressure. (A) Entropy (B) Gibbs energy (C) Internal energy (D) Enthalpy

Last Answer : (B) Gibbs energy