In a flask, colourless N2O4(g) is in equilibrium with brown coloured NO2(g). At equilibrium when the flask is heated to 100C, the brown colour deepens and on cooling it becomes less coloured. Which statement is incorrect about this observation?
1. The H for the reaction N2O4(g) 2NO2(g) is +ve
2. Paramagnetism increases on heating
3. The H-U at 100C is equal to 200 cal
4. Dimerisation is reduced on heating
At 25C, for the process H2O(l)H2O(g);
is 8.6 kJ. The vapour pressure of water at this temperature is nearly:-
1. 24 torr
2. 285 torr
3. 32.17 torr
4. 100 torr
The standard enthalpy of vaporisation vapH for water at 100C is 40.66 kJ mol-1. The
internal energy of vaporisation of water at 100C (in kJ mol-1) is-
(Assume water vapour to behave like an ideal gas)
1. +37.56
2. -43.76
3. +43.76
4. +40.66
When a gas undergoes adiabatic expansion, it gets cooled due to -
1. Loss of energy
2. Fall in pressure
3. Decrease in velocity
4. Increase in energy with work done
A carnot engine having an efficiency of th of heat engine, is used as a refrigerator. If then work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is:
1. 1 J
2. 90 J
3. 99 J
4. 100 J
A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then:
1. | compressing the gas through an adiabatic process will require more work to be done. |
2. | compressing the gas isothermally or adiabatically will require the same amount of work to be done. |
3. | which of the case (whether compression through isothermal or through the adiabatic process) requires more work to be done will depend upon the atomicity of the gas. |
4. | compressing the gas isothermally will require more work to be done. |
Figure below shows two paths that may be taken by a gas to go from a state A to a state C. In process AB, 400 J of heat is added to the system and in process BC, 100 J of heat is added to the system. The heat absorbed by the system in the process AC will be-
(a) 380 J
(b) 500 J
(c) 460 J
(d) 300 J
The coefficient of performance of a refrigerator is 5. If the temperature inside freezer is -20°C, the temperature of the surroundings to which it rejects heat is -
1. 31°C
2. 41°C
3. 11°C
4. 21°C
A thermodynamic system undergoes cyclic process ABCDA as shown in figure. The work done by the system in the cycle is
(1) ρoVo
(2) 2ρoVo
(3) ρoVo/2
(4)zero
An ideal gas goes from state A to state B via three different processes, as indicated in the P-V diagram. If indicates the heat absorbed by the gas along the three processes and indicates the change in internal energy along the three processes respectively, then:
1. | \(\mathrm{Q}_1>\mathrm{Q}_2>\mathrm{Q}_3 \) and \(\Delta \mathrm{U}_1=\Delta \mathrm{U}_2=\Delta \mathrm{U}_3\) |
2. | \(\mathrm{Q}_3>\mathrm{Q}_2>\mathrm{Q}_1\) and \(\Delta \mathrm{U}_1=\Delta \mathrm{U}_2=\Delta \mathrm{U}_3\) |
3. | \(\mathrm{Q}_1=\mathrm{Q}_2=\mathrm{Q}_3\) and \(\Delta \mathrm{U}_1>\Delta \mathrm{U}_2>\Delta \mathrm{U}_3\) |
4. | \(\mathrm{Q}_3>\mathrm{Q}_2>\mathrm{Q}_1\) and \(\Delta \mathrm{U}_1>\Delta \mathrm{U}_2>\Delta \mathrm{U}_3\) |
If represent the increase in internal energy and work done by the system respectively in a thermodynamical process,which of the following is true?
(1) in a adiabatic process
(2) in a isothermal process
(3) in adiabatic process
(4) in a isothermal process
At the value of the density of a fixed mass of an ideal gas divided by its pressure is x. At this ratio is
(1) x
(2)
(3)
(4)
One mole of a real gas is subjected to heating at constant volume from state to state. Then it is subjected to irreversible adiabatic compression against constant external pressure of P3 atm till syatem reaches the final state. If the constant volume molar heat capacity of real gas is CV. Find out correct expression for from state 1 to state 3-
1.
2.
3.
4.
When 0.16 g of glucose was burnt in a bomb calorimeter, the temperature rose by 4 deg. Calculate the calorimeter constant (water equivalent of the calorimeter) given that [molar enthalpy of combustion]. Molar mass of glucose = 180 mol-1.
1.
2.
3.
4.
Heat of neutralisation of oxalic acid is -25.4 K cal mol-1 using strong base, NaOH. Hence enthalpy change of the process is is-
1. 2.0 kcal
2. -11.8 kcal
3. 1.0 kcal
4. -1.0 kcal
5 moles of nitrogen gas are enclosed in an adiabatic cylindrical vessel. The piston itself is a rigid light cylindrical container containing 3 moles of Helium gas. There is a heater which gives out a power 100 cal to the nitrogen gas. A power of 30 cal is transferred to Helium through the bottom surface of the piston.
The rate of increment of temperature of the nitrogen gas assuming that the piston moves slowly :
1. 2K/sec
2. 4K/sec
3. 6K/sec
4. 8K/sec
The intermediate SiH2 is formed in the thermal decomposition of silicon hydrides. Calculate of SiH2 given the following reactions
1. 353 kJ/mol
2. 321 kJ/mol
3. 198 kJ/mol
4. 274 kJ/mol
A certain vessel X has water and nitrogen gas at a total pressure of 2 atm. and 300 K. All the contents of the vessel are transferred to another vessel Y having half the capacity of the vessel X. The pressiure of N2 in this vessel was 3.8 atm. at 300 K. The vessel Y is heated to 320 K and the total pressure observed was 4.32 atm. Calculate the enthalpy of vapourisation of water assuming it to be independent of temperature. Also assume the volume occupied by the gases in a vessel is equal to the volume of the vessel.
1. 39.637 kJ mol-1
2. 19.531 kJ mol-1
3. 396.37 kJ mol-1
4. 3.9127 kJ mol-1
Iodine molecule dissociates into atoms after absorbing light of 4500 . If one quantum of radiation is absorbed by each molecule, calculate the kinetic energy of iodine atoms. Bond energy of I2 is 240 kJ mol-1.
1.
2.
3.
4.