TNPSC Chemistry - Thermochemistry
Exam Duration: 45 Mins Total Questions : 25
Consider the following statements
1. kinetic energy in the energy of motion.
2. Potential energy is stored energy.
3. Fuel gases (as LPG) contain potential energy in their chemical bonds.
Which of the above is/are correct?
- (a)
Only 1
- (b)
Only 2
- (c)
1,2 and 3
- (d)
None of the above
An increase in temperature increases which of the following?
1. The rate constant of a reaction
2. The ionic product of water
3. The equilibrium constant of an exothermic reaction.
Select the correct answer using the codes given below.
- (a)
1 and 2 only
- (b)
2 and 3 only
- (c)
1 and 3 only
- (d)
All of the above
If a refrigerator's door is kept open, then
- (a)
room will be cooled
- (b)
room will be heated
- (c)
room may get cooled or heated depending upon the weather
- (d)
No effect
A fan produces a feeling of comfort during hot weather, because
- (a)
our body radiates more heat in air
- (b)
fan supplies cool air
- (c)
conductivity of air increases
- (d)
our perspiration evaporates rapidly
Which of the following is a closed system?
- (a)
Jet engine
- (b)
Tea placed in steel kettle
- (c)
Pressure cooker
- (d)
Rocket engine during propulsion
Match Column I with Column II.
Column I | Column II |
A. Endothermic | 1. Variation of enthalpy of a reaction temperature |
B. EXothermic | 2. A process or reaction which consumes heat |
C. Activation energy | 3. A process or reaction that releases heat |
D. Arrhenius equation | 4. The amount of energy which must be invested in a reaction to get it started |
Select the correct answer using the codes given below.
- (a)
A B C D 2 3 4 1 - (b)
A B C D 3 4 1 2 - (c)
A B C D 4 1 2 3 - (d)
A B C D 1 2 3 4
In the pressure cooker, cooking is faster because the increase in vapour pressure
- (a)
increases the specific heat
- (b)
decreases the specific heat
- (c)
decreases the boiling point
- (d)
increases the boiling point
Assertion (A) When H2O is added to CaO, heat is liberated.
Reason (R) Reaction between CaO and H2O is exothermic.
- (a)
Both A and R are individually true and R is the correct explanation of A
- (b)
Both A and R are individually true, but R is not the correct explanation of A
- (c)
A is true, but R is false
- (d)
A is false, but R is true
If a system A is in thermal equilibrium with B and B is in thermal equilibrium with C, then A and C are in equilibrium with other. "This is a statement of"
- (a)
cyclic rule
- (b)
zeroth law of thermodynamics
- (c)
first law of thermodynamics
- (d)
second law of thermodynamics
An intensive property in thermodynamics means a property which depends
- (a)
on the amount of the substance only
- (b)
on the nature of the substance only
- (c)
both on the amount as well as nature of the substance
- (d)
neither on the amount nor on the nature
A gas which cannot be collected over water is
- (a)
N2
- (b)
O2
- (c)
SO2
- (d)
PH3
Entropy change of a system and its surrounding in equilibrium
- (a)
increases
- (b)
decreases
- (c)
remains constant
- (d)
either increases or decreases
Match Column I (Thermodynamic Relation/Law) with Column II (Related Term/Concept) and select the correct answer using the codes given below the Columns.
Column I | Column II |
A. First law of thermodynamics | 1. Universal gas constant |
B. Equation of state of an ideal gas | 2. Coefficient of thermal expansion |
C. Thermodynamic disorder | 3. Conservation of energy |
4. Entropy |
- (a)
A B C 3 4 1 - (b)
A B C 2 1 4 - (c)
A B C 3 1 4 - (d)
A B C 2 4 1
In which of the following, the entropy decreases?
- (a)
Crystallisation of sucrose from solution
- (b)
Rusting of iron
- (c)
Melting of ice
- (d)
Vaporization of camphor
Statements I A thermally insulated vessel contains some water. If the vessel is shaken vigorously, the temperature of the water will rise.
Statements II In this process energy is given to the water.
Which one of the following is correct with reference to the above statements?
- (a)
Both Statements I and Statements II are true and Statements II is the correct explanation of Statements I
- (b)
Both Statements I and Statements II are true, but Statements II is not the correct explanation of Statements I
- (c)
Statements I is true, but Statements II is false
- (d)
Both Statements I and Statements II are false
Assertion (A) As solid changes to liquid and then to vapour state, entropy increases.
Reason (R) As going from solid to liquid and then to vapour state, disorder increases.
- (a)
Both A and R are individually true and R is the correct explanation of A
- (b)
Both A and R are individually true, but R is not the correct explanation of A
- (c)
A is true, but R is false
- (d)
A is false, but R is true
During the evaporation of a liquid
- (a)
the enthalpy decreases
- (b)
the enthalpy increases
- (c)
the internal energy decreases
- (d)
the enthalpy remains unchanged
During isothermal expansion of an ideal gas, its
- (a)
enthalpy reduces to zero
- (b)
enthalpy decreases
- (c)
internal energy increases
- (d)
enthalpy remains unaffected
Which law of the thermodynamics introduces the concept of entropy?
- (a)
Second law
- (b)
Zeroth law
- (c)
Third law
- (d)
First law
Combustion of a candle is
- (a)
physical change
- (b)
reduction reaction
- (c)
endothermic reaction
- (d)
exothermic reaction
When ammonium chloride is dissolved in water, the solution becomes cold. The change is
- (a)
endothermic
- (b)
exothermic
- (c)
super cooling
- (d)
None of the above
The entropy of perfectly crystalline solid absolute zero is
- (a)
positive
- (b)
negative
- (c)
zero
- (d)
not definite
If a reaction is carried out at constant pressure, which of the following statements is correct?
- (a)
The reaction is likely to be endothermic
- (b)
The heat change is equal to the enthalpy change
- (c)
The reaction is likely to be exothermic
- (d)
The heat change is equal to the change in temperature
Consider the following statements
1. An ideal fuel should have high calorific value, low ignition temperature, regulated and controlled.
2. Born-Haber cycle is used to determine lattice energy.
Which of the statement(s) given above is/are correct?
- (a)
Only 1
- (b)
Only 2
- (c)
1 and 2
- (d)
None of these
Consider the following statements
1. Water and ethanol have unusually large entropies of vaporisation.
2.The compound with negative heat of formation is known as exothermic compound.
Which of the statement(s) given above is/are correct?
- (a)
Only 1
- (b)
Only 2
- (c)
1 and 2
- (d)
None of the above