Related InterviewSolutions

• A process is taking place at constant temperature and pressure. ThenA. `DeltaH`B. `DeltaH=TDeltaS`C. `DeltaH=0`D. `DeltaS=0`
• A reaction cannot take place spontaneously at any temperture whenA. both `DeltaH` and `DeltaS` are positiveB. both `DeltaH` and `DeltaS` are negativeC. `DeltaH` is negative and `DeltaS` is positiveD. `DeltaH` is zero and `DeltaS` is positive
• Assertion(A) : Absolute value of `H` cannot be determined. Reason(R ) : Absolute value of `E` cannot be determined.A. Both `A`and `R` are true and `R` is the correct explantion of `A`B. Both `A`and `R` are true and `R` is not a correct explantion of `A`C. `A` is true but `R` is falseD. `A` is false but `R` is true
• Assertion(A) : Decrease of free energy during the process under particular conditions provides a measure of its spontaneity. Reason(R ) : A spontaneous change must have +ve sign of `DeltaS_("total")`.A. Both `A`and `R` are true and `R` is the correct explantion of `A`B. Both `A`and `R` are true and `R` is not a correct explantion of `A`C. `A` is true but `R` is falseD. `A` is false but `R` is true
• Assertion:Absolute values of intenal energy of substances cannot be determined. Reason:It is impossible to determine exact values of constituent energies of the substances.A. Both `A`and `R` are true and `R` is the correct explantion of `A`B. Both `A`and `R` are true and `R` is not a correct explantion of `A`C. `A` is true but `R` is falseD. `A` is false but `R` is true
• Assertion(A) : Two systems which are both in thermal equilibrium with the third system are in thermal equilibrium with one another. Reason(R ) : The heat flows spontaneously from a system at high temperature to a system at low temperature.A. Both `A`and `R` are true and `R` is the correct explantion of `A`B. Both `A`and `R` are true and `R` is not a correct explantion of `A`C. `A` is true but `R` is falseD. `A` is false but `R` is true
• A sample consisting of `1mol` of a mono-atomic perfect gas `(C_(V) = (3)/(2)R)` is taken through the cycle as shown. Temperature at points `(1),(2)` and `(3)` respectively isA. `273K`, `546K`, `273K`B. `546K`, `273K`, `273K`C. `273K`, `273K`, `273K`D. `546K`, `546K`, `273K`
• Energy is associated with the orientation and distribution of molecules in space. Disordered crystals have higher entropy than ordered crystals and diffused gases have higher entropy than compressed gases. Entropy is also associated with molecular motion. As the temperature of a substance increases, random molecular motion increases hence entropy increases. Figure gives variation of entropy with temperature. At absolute zero `(-273^(@)C)` every substance is in solid state whose particles are rigidly fixed in a crystalline structure. If there is no residual orientational disorder, like that in `CO`, entropy of the substance is zero. Third law of thermodynamics states. At the absolute zero of temperature the entropy of every substance become zero and does become zero in case of perfectly crystalline structure. `understand(T to 0)(LtS)=0` In case of `CO` and `NO` molecules in solid state, there is randomness even at `0 K` due to their dipole moments hence entropy in such cases is not zero even at `0 K`. As the temperature is raised, the molecules begin to vibrate. The number of ways in which the vibrational energy can be distributed increases with increases in temperature and the entropy of solid increases steadily as the temperature increaes. At the melting point (mp) of the solid, there is a discontinous jump in entropy because there are many more ways of arranging the molecules in the liquid than in the solid. An even greater jump in entropy is observed at the boiling point (bp) because molecules in the gas are to free to occupy a more larger volume and randomness increases. From the figure representing enthalpy change of various transitions as indicated, a substance has maximum enthalpy present in A. Solid stateB. Liquid stateC. Gaseous stateD. Equal in all states.
• Energy is associated with the orientation and distribution of molecules in space. Disordered crystals have higher entropy than ordered crystals and diffused gases have higher entropy than compressed gases. Entropy is also associated with molecular motion. As the temperature of a substance increases, random molecular motion increases hence entropy increases. Figure gives variation of entropy with temperature. At absolute zero `(-273^(@)C)` every substance is in solid state whose particles are rigidly fixed in a crystalline structure. If there is no residual orientational disorder, like that in `CO`, entropy of the substance is zero. Third law of thermodynamics states. At the absolute zero of temperature the entropy of every substance become zero and does become zero in case of perfectly crystalline structure. `understand(T to 0)(LtS)=0` In case of `CO` and `NO` molecules in solid state, there is randomness even at `0 K` due to their dipole moments hence entropy in such cases is not zero even at `0 K`. As the temperature is raised, the molecules begin to vibrate. The number of ways in which the vibrational energy can be distributed increases with increases in temperature and the entropy of solid increases steadily as the temperature increaes. At the melting point (mp) of the solid, there is a discontinous jump in entropy because there are many more ways of arranging the molecules in the liquid than in the solid. An even greater jump in entropy is observed at the boiling point (bp) because molecules in the gas are to free to occupy a more larger volume and randomness increases. Which of the following process is spontaneous?A. Diffusion of perfume molecules from one side of the room to the otherB. Decomposition of solid `CaCO_(3)`C. Heat flow from a cold object to a hot objectD. Climbing up a mountain.
• Energy is associated with the orientation and distribution of molecules in space. Disordered crystals have higher entropy than ordered crystals and diffused gases have higher entropy than compressed gases. Entropy is also associated with molecular motion. As the temperature of a substance increases, random molecular motion increases hence entropy increases. Figure gives variation of entropy with temperature. At absolute zero `(-273^(@)C)` every substance is in solid state whose particles are rigidly fixed in a crystalline structure. If there is no residual orientational disorder, like that in `CO`, entropy of the substance is zero. Third law of thermodynamics states. At the absolute zero of temperature the entropy of every substance become zero and does become zero in case of perfectly crystalline structure. `understand(T to 0)(LtS)=0` In case of `CO` and `NO` molecules in solid state, there is randomness even at `0 K` due to their dipole moments hence entropy in such cases is not zero even at `0 K`. As the temperature is raised, the molecules begin to vibrate. The number of ways in which the vibrational energy can be distributed increases with increases in temperature and the entropy of solid increases steadily as the temperature increaes. At the melting point (mp) of the solid, there is a discontinous jump in entropy because there are many more ways of arranging the molecules in the liquid than in the solid. An even greater jump in entropy is observed at the boiling point (bp) because molecules in the gas are to free to occupy a more larger volume and randomness increases. Which has maximum entropy of vaporisation ?A. Ethanol `(l)`B. Benzene `(l)`C. Toluene `(l)`D. `CO_(2)(g)`