Thermodynamics CBSE Questions & Answers

Thermodynamics

This is Chemistry Class 11 Thermodynamics CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
According to Hess’s Law if a reaction takes place in several steps then its standard reaction enthalpy is
  • A
    the sum of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at 35\(^\circ {\text{ C}}\)
  • B
    the sum of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at 2 bar
  • C
    the sum of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at the same temperature
    Correct
  • D
    the difference of the standard enthalpies of the intermediate reactions into which the overall reaction may be divided at the same temperature
2
Enthalpy of atomization is enthalpy change on breaking
  • A
    one kg of bonds completely to obtain atoms in the gas phase
  • B
    one kg of bonds completely to obtain atoms in the liquid phase
  • C
    One mole of bonds completely to obtain atoms in the liquid phase
  • D
    One mole of bonds completely to obtain atoms in the gas phase
    Correct
3
In the case of compounds such as \({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{Cl}},{\text{ C}}{{\text{H}}_{\text{3}}}{\text{N}}{{\text{O}}_{\text{2}}}\)etc which of the following is used as Bond enthalpy
  • A
    Mean bond enthalpy
    Correct
  • B
    Minimum bond enthalpy
  • C
    Maximum bond enthalpy
  • D
    Bond dissociation enthalpy
4
Enthalpy of solution of a substance is the enthalpy change
  • A
    when one kg of it dissolves in a specified amount of solvent
  • B
    when one kg of it reacts with a specified amount of solvent
  • C
    when one mole of it dissolves in a specified amount of solvent
    Correct
  • D
    when one mole of it reacts with a specified amount of solvent
5
The lattice enthalpy of an ionic compound is the
  • A
    enthalpy change which occurs when one mole of an ionic compound dissociates into its ions in liquid state
  • B
    enthalpy change which occurs when one gm of an ionic compound dissociates into its ions in gaseous state
  • C
    enthalpy change which occurs when one mole of an ionic compound dissociates into its ions in gaseous state
    Correct
  • D
    enthalpy change which occurs when one kg of an ionic compound dissociates into its ions in liquid state
6
Spontaneity in the context of chemical thermodynamics means
  • A
    having the potential to proceed with the assistance of external agency
  • B
    having the potential to proceed instantaneously
  • C
    having the potential to proceed fast
  • D
    having the potential to proceed without the assistance of external agency
    Correct
7
Entropy is a state function and measures
  • A
    the degree of randomness or disorder in the system
    Correct
  • B
    the enthalpy of the system
  • C
    the internal energy of the system
  • D
    the degree of regularity or order in the system
8
We can calculate the change in entropy of a reversible process by
  • A
    \(\Delta {S_{sys}} = RT{q_{sys,rev}}\)
  • B
    \(\Delta {S_{sys}} = \frac{{{q_{sys,rev}}}}{T}\)
    Correct
  • C
    \(\Delta {S_{sys}} = \frac{{{q_{sys,rev}}}}{{2T}}\)
  • D
    \(\Delta {S_{sys}} = T{q_{sys,rev}}\)
9
If change in Gibbs energy \(\Delta {\text{G}}\) is negative (< 0)
  • A
    the process is non spontaneous
  • B
    the process is spontaneous
    Correct
  • C
    the process will rarely take place
  • D
    the process will never take place
10
Gibbs energy for a reaction in which all reactants and products are in standard state, \({\Delta _{\text{r}}}{{\text{G}}^0}\)is related to the equilibrium constant of the reaction as follows:
  • A
    \({\Delta _{\text{r}}}{{\text{G}}^0}\)= -nRTln K
  • B
    \({\Delta _{\text{r}}}{{\text{G}}^0}\) = -Tln K
  • C
    \({\Delta _{\text{r}}}{{\text{G}}^0}\) = -Rln K
  • D
    \({\Delta _{\text{r}}}{{\text{G}}^0}\) = -RTln K
    Correct
11
A thermodynamic state function is a physical quantity
  • A
    used to determine heat changes
  • B
    used to determine pressure volume work
  • C
    whose value is independent of path
    Correct
  • D
    whose value depends on temperature only
12
For the process to occur under adiabatic conditions, the correct condition is:
  • A
    \(\Delta {\text{p}}\) = 0
  • B
    q = 0
    Correct
  • C
    w = 0
  • D
    \(\Delta {\text{T}}\) = 0
13
The enthalpies of all elements in their standard states are:
  • A
    unity
  • B
    different for each element
  • C
    < 0
  • D
    zero
    Correct
14
\(\Delta {{\text{U}}^0}\)of combustion of methane is - X kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\). The value of \(\Delta {{\text{H}}^0}\)is
  • A
    \( < {\text{ }}\Delta {{\text{U}}^0}\)
    Correct
  • B
    zero
  • C
    = \(\Delta {{\text{U}}^0}\)
  • D
    > \(\Delta {{\text{U}}^0}\)
15
The enthalpy of combustion of methane, graphite and dihydrogen at \({\text{298}}^\circ \) K are, ---890.3 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\)393.5 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\), and –285.8 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\) respectively. Enthalpy of formation of \({\text{C}}{{\text{H}}_{\text{4}}}\) (g) will be
  • A
    +52.26 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\)
  • B
    +74.8 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\)
  • C
    - 52.27 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\)
  • D
    - 74.8 kJ \({\text{mo}}{{\text{l}}^{ - {\text{1}}}}\)
    Correct