Thermodynamics and Chemical Energetics AFCAT Questions

AFCAT Chemistry

Thermodynamics and Chemical Energetics MCQ Questions


13.
Dissolution of NH₄NO₃ in water makes the solution colder. This indicates the process is:
A.
Exothermic
B.
Endothermic
C.
Has ΔH = 0
D.
Adiabatic
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ANSWER :
B. Endothermic
14.
Which of the following is an exothermic reaction?
A.
Decomposition of water by electrolysis
B.
N₂ + O₂ → 2NO
C.
Burning of magnesium ribbon
D.
Melting of wax
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ANSWER :
C. Burning of magnesium ribbon
15.
Which sign convention is used by IUPAC for heat absorbed by the system?
A.
q is negative
B.
q is positive
C.
q is zero
D.
Both positive and negative
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ANSWER :
B. q is positive
16.
Enthalpy (H) is defined as:
A.
U + PV
B.
U - PV
C.
U × PV
D.
U/PV
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ANSWER :
A. U + PV
17.
At constant pressure, ΔH equals:
A.
qp (heat at constant pressure)
B.
qv (heat at constant volume)
C.
ΔU only
D.
Always zero
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ANSWER :
A. qp (heat at constant pressure)
18.
The relationship between ΔH and ΔU at constant pressure is:
A.
ΔH = ΔU - PΔV
B.
ΔH = ΔU/RT
C.
ΔH = ΔU × PV
D.
ΔH = ΔU + ΔngRT
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ANSWER :
D. ΔH = ΔU + ΔngRT