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: The enthalpy of formation of gaseous oxygen molecules at `298K` and under1 atm is zero. Reason: The entropy of formation of gaseous oxygen
Last Answer : Assertion: The enthalpy of formation of gaseous oxygen molecules at `298K` and under1 atm is zero. ... D. If both Assertion & Reason are false.
Description : Out of carbon(diamond)and carbon (graphite) whose enthalpy of formation is taken as zero?
Last Answer : Ans. Enthalpy of formation of carbon in the form of graphite is taken as zero because it is a more commonly found in stable form of carbon.
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 : Graphite is used as anode and not diamond. Assign reason.
Last Answer : Ans. In graphite there are free electrons which helps in electricalconductivity.
Description : Assertion :- Water in liquid state is more stable than ice at room temperature. Reason :- Water in liquid from has higher entropy than ice.
Last Answer : Assertion :- Water in liquid state is more stable than ice at room temperature. Reason :- Water in ... . D. If both Assertion & Reason are false.
Description : Assertion(A): Per capita Income is not a useful criterion and should not be used as measure of development. Reason( R) :Kerala with lower per capita income has a better human development ranking than Haryana. a) Both A ... of A. c) A is correct but R is wrong. d) A is wrong but R is correct.
Last Answer : b) Both A and R are true and R is the not correct explanation of A.
Description : Assertion :- Absolute value of enthalpy can not be determined. Reason :- Enthalpy is defined as H = E + PV, and value of internal energy can not be de
Last Answer : Assertion :- Absolute value of enthalpy can not be determined. Reason :- Enthalpy is defined as H = ... . D. If both Assertion & Reason are false.
Description : Assertion :- Entropy is always constant for a closed system. Reason :- Closed system is always reversible.
Last Answer : Assertion :- Entropy is always constant for a closed system. Reason :- Closed system is always ... D. If both Assertion & Reason are false.
Description : Assertion :- In an isolated system the entropy increases due to spontanous process. Reason :- The processes in an isolated system are adiabatic.
Last Answer : Assertion :- In an isolated system the entropy increases due to spontanous process. Reason :- The ... D. If both Assertion & Reason are false.
Description : Assertion :- When a rubber band is stretched entropy increases. Reason :- During expansion entropy increases.
Last Answer : Assertion :- When a rubber band is stretched entropy increases. Reason :- During expansion entropy ... D. If both Assertion & Reason are false.
Description : Assertion (A): Oil as a cutting fluid result in a lower coefficient of friction. Reason (R): Oil forms a thin liquid film between the tool face and chip, and it provides 'hydrodynamic lubrication'. [IES- 2000] (a ... explanation of A (c) A is true but R is false (d) A is false but R is true
Last Answer : (c) A is true but R is false
Description : The enthalpy change for the reaction `2C("graphite")+3H_(2)(g)rarrC_(2)H_(6)(g)` is called
Last Answer : The enthalpy change for the reaction `2C("graphite")+3H_(2)(g)rarrC_(2)H_(6)(g ... combustion C. Enthalpy of hydrogenation D. Enthalpy of vaporisation
Description : Given standard enthalpy of formation of `CO(-110 "KJ mol"^(-1))` and `CO_(2)(-394 "KJ mol"^(-1))`. The heat of combustion when one mole of graphite bu
Last Answer : Given standard enthalpy of formation of `CO(-110 "KJ mol"^(-1))` and `CO_(2)(-394 "KJ mol"^(-1))`. The heat ... B. `-284` KJ C. `-394` KJ D. `-504` KJ
Description : In which of the following reactions, standard reaction entropy change (S°) is positive and standard Gibb's energy change (G°) decreases sharply with increasing temperature? (1) 2 2 1 1 1 C graphite O (g) CO (g) 2 2 2 (2) 2 1 C ... CO(g) O (g) CO (g) 2 (4) 2 1 Mg(s) O (g) MgO(s) 2
Last Answer : C graphite O (g) CO(g)
Description : Pick out the correct statement: (A) In an isothermal system, irreversible work is more than reversible work (B) Under reversible conditions, the adiabatic work is less than isothermal work (C) ... state functions' (D) Matter and energy cannot be exchanged with the surroundings in a closed system
Last Answer : (B) Under reversible conditions, the adiabatic work is less than isothermal work
Description : Why is graphite softer than diamond?
Last Answer : The crystalline structure of graphite and diamond are very different.
Description : Diamond is harder than graphite because of – (1) difference in layers of atoms (2) tetrahedral structure of diamond (3) difference of crystalline structures (4) None of these
Last Answer : (1) difference in layers of atoms Explanation: Diamond is harder than graphite because diamond has a more complex structure. Diamond's structure is like many pentagons connected together, each pentagon ... together in some way. Graphite's structure is very loose, with its bonds forming layers.
Description : Diamond is harder than graphite because of : (1) difference in layers of atoms (2) tetrahedral structure of diamond (3) difference of crystalline structures (4) None of these
Last Answer : difference in layers of atoms
Description : The enthalpy change for a given reaction at `298 K` is `-x cal mol^(-1)`. If the reaction occurs spontaneously at `298 K`, the entropy change at that
Last Answer : The enthalpy change for a given reaction at `298 K` is `-x cal mol^(-1)`. If the reaction occurs ... (-1)` C. Cannot be negative D. Cannot be positive
Description : If the enthalpy of vaporisation of water is `186.5 J mol^(-1)`, then entropy of its vaporisation will be
Last Answer : If the enthalpy of vaporisation of water is `186.5 J mol^(-1)`, then entropy of its vaporisation will be A. `0.5 ... (-1)` D. `2.0KJK^(-1)"mole"^(-1)`
Description : The enthalpy and entropy change for the reaction, `Br_(2)(l)+Cl_(2)(g)rarr2BrCl(g)` are `30KJmol^(-1)` and `105JK^(-1)mol^(-1)` respectively. The temp
Last Answer : The enthalpy and entropy change for the reaction, `Br_(2)(l)+Cl_(2)(g)rarr2BrCl(g)` are `30KJmol^(-1)` and ` ... 285.7 K B. 273 K C. 450 K D. 300 K
Description : If a reaction has an enthalpy of -54.32 kJ/mol and an entropy of -354.2 J/(K*mol), what is the Gibbs free Energy at 54.3(degrees c)?
Last Answer : DeltaG = DeltaH - TDeltaS dG = -54.32 kJ/mol - (54'32+273)K(-354.2J/molK) NB Thevtemperature is quoted in Kelvin(K) and the Entropy must be converted to kJ by dividing by '1000'/ Hence dG = ... 115.94 kJ/mol dG = (+)61.61 kJ/mol Since dG is positive, the reaction is NOT thermodynamically feasible.
Description : Vertical lines on pressure-enthalpy chart show constant (a) pressure lines (b) temperature lines (c) total heat lines (d) entropy lines
Last Answer : Ans: c
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 : Short horizontal lines on pressure-enthalpy chart show (a) constant pressure lines (b) constant temperature lines (c) constant total heat lines (d) constant entropy lines
Description : The heat content of air is called the _____ of the air. a. Temperature b. Humidity c. Enthalpy d. Psychrometry e. Entropy
Last Answer : ANSWER : C
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 : _____ is the amount of uncertainty in a system of symbols A. Bandwidth B. Enthalpy C. Entropy D. Quantum
Last Answer : C. Entropy
Description : What is meant by entropy driven reaction? How can the reaction with positive change of enthalpy and entropy be made entropy driven?
Last Answer : Ans.The free energy change of a reaction is given by ΔG = ΔH - TΔS For a reaction to be spontaneous, ΔG should be -ve. If both ΔH and ΔS are positive ΔG can be -ve if TΔS>ΔH in magnitude. Thus, entropy ... is low, TΔS should be greater than ΔH (ii) If ΔS is small, T should be so large that TΔS>ΔH.
Description : (i)State why heat changes in physical and chemical processes are indicated by enthalpy changes and not by entropy changes? (ii)What are the limitations of First Law of thermodynamics?
Last Answer : (i) Most of the processes are carried out in an open system i.e, at constant pressure. (ii)(a) Can’t explain the feasibility of the reaction. (b)It poses no restriction on the direction of flow of heat. (c)Practically it is not possible to convert the heat energy into an equivalent amount of work.
Description : Mollier diagram is a plot of (A) Temperature vs. enthalpy (B) Temperature vs. enthalpy (C) Entropy vs. enthalpy (D) Temperature vs. internal energy
Last Answer : (C) Entropy vs. enthalpy
Description : Isentropic process means a constant __________ process. (A) Enthalpy (B) Pressure (C) Entropy (D) None of these
Last Answer : (C) Entropy
Description : Throttling (Joule-Thomson effect) process is a constant __________ process. (A) Enthalpy (B) Entropy (C) Pressure (D) None of these
Last Answer : (A) Enthalpy
Description : __________ decreases during adiabatic throttling of a perfect gas. (A) Entropy (B) Temperature (C) Enthalpy (D) Pressure
Last Answer : (D) Pressure
Description : Entropy change of the reaction, H2O (liquid) → H2O (gas), is termed as the enthalpy of (A) Solution (B) Vaporisation (C) Formation (D) Sublimation
Last Answer : (B) Vaporisation
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
Description : The extensive properties are (A) Volume, mass and number of moles (B) Free energy, entropy and enthalpy (C) Both (A) and (B) (D) None of these
Last Answer : (C) Both (A) and (B)
Description : Throttling process is a/an __________ process. (A) Reversible and isothermal (B) Irreversible and constant enthalpy (C) Reversible and constant entropy (D) Reversible and constant enthalpy
Last Answer : (B) Irreversible and constant enthalpy
Description : High pressure steam is expanded adiabatically and reversibly through a well insulated turbine, which produces some shaft work. If the enthalpy change and entropy change across the turbine are represented by ΔH and ΔS respectively for this process: ... (C) Δ H ≠ 0 and ΔS ≠ 0 (D) Δ H = 0 and ΔS ≠ 0
Last Answer : (B) Δ H ≠ 0 and ΔS = 0
Description : During Joule-Thomson expansion of gases (A) Enthalpy remains constant (B) Entropy remains constant (C) Temperature remains constant (D) None of these
Last Answer : (A) Enthalpy remains constant
Description : Mollier chart is a __________ plot. (A) Pressure vs. enthalpy (B) Pressure vs. volume (C) Enthalpy vs. entropy (D) Temperature vs. entropy
Last Answer : (C) Enthalpy vs. entropy
Description : Joule-Thomson effect i.e., a throttling process is a constant __________ process. (A) Entropy (B) Temperature (C) Internal energy (D) Enthalpy
Last Answer : (D) Enthalpy
Description : Specific __________ does not change during a phase change (e.g. sublimation, melting, vaporisation etc.). (A) Entropy (B) Internal energy (C) Enthalpy (D) Gibbs free energy
Last Answer : (D) Gibbs free energy
Description : For an incompressible fluid, the __________ is a function of both pressure as well as temperature. (A) Internal energy (B) Enthalpy (C) Entropy (D) All (A), (B) & (C)
Last Answer : (B) Enthalpy
Description : Pick out the correct statement. (A) Entropy and enthalpy are path functions (B) In a closed system, the energy can be exchanged with the surrounding, while matter cannot be exchanged (C) All the natural processes are reversible in nature (D) Work is a state function
Last Answer : (C) All the natural processes are reversible in nature
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 : If a solid is compressed adiabatically in its elastic range, its __________ remains constant (A) Internal energy (B) Enthalpy (C) Entropy (D) Temperature
Description : For a thermodynamic system undergoing a process, which of the following pairs best expresses the relationship similar to that expressed by the pressure volume plot? (A) Temperature - entropy (B) Temperature - pressure (C) Enthalpy - entropy
Last Answer : (A) Temperature - entropy