UNIT 7: Thermodynamics - Online Test
Q1. The
temperature of the system, decreases in an ___________________
Answer : Option C
Explaination / Solution:
No Explaination.
Q2. In
an isothermal reversible compression of an ideal gas the sign of q, ∆S and w
are respectively
Answer : Option D
Explaination / Solution:
During compression, energy of the system increases,
in isothermal condition, to main-tain temperature constant, heat is liberated
from the system. Hence q is negative.
During compression entropy decreases.
During compression work is done on the system,
hence w is positive
Q3. Molar
heat of vapourisation of a liquid is 4.8 kJ mol–1. If the entropy
change is 16 J mol–1 K–1, the boiling point of the liquid
is
Answer : Option B
Explaination / Solution:
Q4. ∆S
is expected to be maximum for the reaction
Answer : Option D
Explaination / Solution:
In
CaCO3(S) → CaO(S) + CO2(g), entropy change is
positive. In (a) and (b) entropy change is negative ; in (c) entropy change is
zero.
Q5. The
values of ∆H and ∆S for a reaction are respectively 30 kJ mol–1 and
100 JK–1 mol–1. Then the temperature above which the
reaction will become spontaneous is
Answer : Option A
Explaination / Solution:
∆G = ∆H – T ∆ S
At 300K
∆G =30000 J mol–1 – 300 K x 100 J K–1
mol–1
∆G = 0
above 300 K ; ∆G will be negative and reaction
becomes spontaneous.
