laboursonline – MCQs, Mock Tests | IIT JEE IIT JEE Chemical Energetics And Thermodynamics

A negative sign of the free energy change denotes that

1. the system is in constant equilibrium
2. the reaction is very much unlikely
3. the reaction is non-spontaneous
4. the reaction tends to proceed spontaneously

✅ Correct Answer: 4

For a reversible process the total entropy change

1. increases
2. is constant
3. decreases
4. is zero

✅ Correct Answer: 2

The heat of neutralization of a strong acid by a strong base

1. is greater than 13.7 Kcal
2. is less than 13.7 Kcal
3. is nearly 13.7 Kcal
4. depends upon the nature of the acid

✅ Correct Answer: 3

Entropy of the universe is always

1. increasing
2. decreasing
3. constant
4. five

✅ Correct Answer: 1

The factor that does not influence the heat of reaction is

1. method by which reactants change to products
2. chemical state of the reactants and products
3. whether it is taking place at constant temperature
4. All the above

✅ Correct Answer: 4

The highest temperature at which vapour pressure of a liquid can be measured is

1. the boiling point of the liquid
2. critical solution temperature
3. ionisation temperature
4. inversion temperature

✅ Correct Answer: 1

On dissolving sodium chloride in water there is

1. increase in entropy
2. increase in the free energy
3. decrease in entropy
4. No change in enthalpy

✅ Correct Answer: 1

n a spontaneous irreversible process the total entropy of the system & its surroundings

1. is constant
2. decreases
3. increases
4. is zero

✅ Correct Answer: 3

Heat of reaction

1. depends on the rate of reaction
2. depends on pressure
3. is independent of temperature
4. may or may not depend on temperature

✅ Correct Answer: 3

On dissolving magnesium sulphate in water

1. no change in entropy
2. entropy decreases
3. entropy increases
4. nothing can be said

✅ Correct Answer: 2

Which out of the following represents a closed system?

1. Hot water contained in a closed container
2. Hot water contained in open container
3. Water in a closed insulated container in equilibrium with its vapours
4. None of the above

✅ Correct Answer: 1

A person requires 2870 Kcal of energy for leading a normal life. If heat of combustion of cane sugar is -1349 Kcal then he must consume??kg of cane sugar daily.

1. 728
2. 448
3. 142
4. 224

✅ Correct Answer: 1

1 Joule is equal to

1. 2.39 Cal
2. 0.04184 Cal
3. 1.390 Cal
4. 0.239 Cal

✅ Correct Answer: 4

According to Hess Law the thermal effects of a reaction depend upon

1. initial and final conditions of reactants and products
2. final conditions of products
3. intermediate stage of reaction
4. None of these

✅ Correct Answer: 1

The process in which no heat change takes place is

1. an irreversible process
2. an isothermal process
3. a reversible process
4. an adiabatic process

✅ Correct Answer: 4

If temperature is kept constant during the reaction the process is said to be?.

1. Adiabatic
2. Isobaric
3. Isothermal
4. None of the above

✅ Correct Answer: 3

The heat of formation is the change in enthalpy accompanying the formation of a substance from its elements at 298 K and 1 atmospheric pressure. Since the enthalpies of elements are taken to be zero the heat of formation of the compound may be

1. always positive
2. always negative
3. positive or negative
4. zero

✅ Correct Answer: 3

Heat of fusion of a molecular solid is

1. high
2. low
3. average
4. very high

✅ Correct Answer: 2

Evaporation of water is a spontaneous process although it is

1. an endothermic in nature
2. a photochemical reaction
3. an exothermic in nature
4. proceeds without heat loss or heat gain

✅ Correct Answer: 1

On heating a liquid at its boiling point

1. temperature of the liquid increases
2. enthalpy increases
3. activation energy increases
4. entropy of the system increases

✅ Correct Answer: 4

Heat of neutralisation of HCl and NaOH is -57.32 kJ per gram equivalent and that of acetic acid and NaOH is -55.23 kJ per gram equivalent. The heat of dissociation of acetic acid per gram equivalent should be

1. -2.09
2. 2.09
3. -2.196
4. 2.196

✅ Correct Answer: 2

n burning hydrogen in an atmosphere of chlorine 1.65 gm of HCl was obtained and 1 Kcal of heat was liberated. The heat of formation of HCl should be:

1. -21.12 Kcal/mol
2. -44.2 Kcal/mol
3. 500 cal/mol
4. 500 cal/gm

✅ Correct Answer: 1

The apparatus used for measuring the heat changes is known as

1. Thermometer
2. Ammeter
3. Voltmeter
4. Calorimeter

✅ Correct Answer: 4

The enthalpy of the elements in their standard states is taken as zero. So the enthalpy of formation of a compound may be

1. negative
2. positive
3. zero
4. negative or positive

✅ Correct Answer: 4

Which of the following will have maximum entropy?

1. Argon
2. Helium
3. Silver
4. Diamond

✅ Correct Answer: 2

Internal energy of the elements is assigned a value of??.cal per mole at standard states.

1. 5
2. 9
3. 99
4. 0

✅ Correct Answer: 4

Entropy of a substance is Zero at

1. the temp. at which a substance is in the liquid state
2. standard states i.e. 25 degreeCentigrade
3. absolute zero
4. 0 degreeCentigrade

✅ Correct Answer: 3

10 gm of ice at 0 degreeCentigrade is placed into 100 gm of water at 50 degreeCentigrade. The temperature of water after the whole ice has melted will be

1. 32.8 degreeCentigrade
2. 19.5 degreeCentigrade
3. 31.8 degreeCentigrade
4. 38.1 degreeCentigrade

✅ Correct Answer: 4

What is true about entropy?

1. Entropy of universe increases and tends towards maximum value
2. Entropy of universe decreases and tends to be zero
3. Entropy of universe always remain constant
4. Increases and decreases with a periodic rate.

✅ Correct Answer: 1

All naturally occurring processes proceed spontaneously in a direction which leads to

1. increase in enthalpy of system
2. decrease in entropy of system
3. decrease in free energy of system
4. increase in free energy of system.

✅ Correct Answer: 3

Which of the following processes proceed with increase of entropy?I. solid changing into liquidII. expansion of gasIII. dissolution of solid in liquidIV. polymerization.

1. Only I
2. IIIIII
3. IIIII
4. IIIIV

✅ Correct Answer: 2

The heat of solution depends upon

1. nature of solute
2. nature of solvent
3. concentration of solution
4. All the above

✅ Correct Answer: 4

The vaporization process is always

1. exothermic
2. endothermic
3. can be exothermic or endothermic
4. isoentropic.

✅ Correct Answer: 2

The free energy change occurring during the irreversible process is

1. negative
2. positive
3. dependent on whether the process is exothermic or endothermic
4. negative only if the process is exothermic.

✅ Correct Answer: 1

Calorific values of food and fuel are determined by

1. Bomb calorimeter
2. Bunsens ice calorimeter
3. Backmanns thermometer
4. None of the above

✅ Correct Answer: 1

Enthalpy of reaction? is the heat change accompanuing the conversion of

1. 1 mole of reactants into products
2. 1 gm of reactants into products
3. Number of moles of reactants into products as are indicated by the balanced equation of the process
4. 22.4 L of reactants at N.T.P. into products.

✅ Correct Answer: 3

Internal energy of a given mass of an ideal gas depends upon

1. Temperature
2. Pressure
3. Volume
4. On all the above factors.

✅ Correct Answer: 1

The heat of reaction depends upon

1. ctemperature of the reaction
2. physical states of reactants and products
3. both a and b
4. path of the reaction and temperature.

✅ Correct Answer: 3

Which statement is not applicable to thermochemical equations?I. They represent chemical change as well as heat changeII. They give the idea about mechanism of the processIII. They depict the spontaneity of the processIV. Exothermic or endothermic nature of reaction.

1. II IV
2. III I
3. III I
4. II III

✅ Correct Answer: 4

All the naturally occurring processes proceed spontaineously in a direction which leads to

1. increase in enthalpy of system
2. decrease in entropy of system
3. increase in entropy of system
4. increase in entropy of universe

✅ Correct Answer: 4

The heat change in a reaction does not depend upon the

1. conditions under which reaction is carried
2. state of reactants and products
3. number of intermediate stages involved
4. state of reactants and products

✅ Correct Answer: 3

In which of the following process entropy increases?I. Rusting of ironII. Vaporisation of CamphorIII. Crystallisation of sugar from syrupIV. Atomisation of dihydrogen.

1. I II
2. II III
3. I IV
4. Only IV

✅ Correct Answer: 3

When a solid melts there is

1. an increase in entropy
2. an increase in enthalpy
3. a decrease in internal energy
4. Both (A) and (B) are correct.

✅ Correct Answer: 4

Absorption of heat occurs when

1. carbon burns in air
2. sulphur dioxide is oxidised to sulphur trioxide
3. ammonium chloride dissolves s in water
4. cooking gas is burnt.

✅ Correct Answer: 3

A system absorbs 20 kJ of heat and also does 10 kJ of work. The net internal energy of the system

1. increases by 10 kJ
2. decreases by 10 kJ
3. increases by 30 kJ
4. decreases by 30 kJ

✅ Correct Answer: 3

Thermodynamic parameter which is a state function and is also used to measure disorder of the system is

1. Entropy
2. Fugacity
3. Viscosity
4. Periodicity

✅ Correct Answer: 1

In naturally occurring changes a system tends to alter in such a way that the entropy of the system

1. increases
2. decreases
3. remains constant
4. is reduced to zero

✅ Correct Answer: 1

In thermodynamics a quantity whose value simply depends upon the initial and final state of the system is called

1. thermolynamic quantity
2. state function
3. adiabatic quantity
4. path function.

✅ Correct Answer: 2

Thermochemistry is the study of relationship between heat energy and

1. activation energy
2. friction energy
3. chemical energy
4. Gibbs energy

✅ Correct Answer: 3

The enthalpy of formation of the compound is

1. always + ve
2. always - ve
3. can be + ve or - ve
4. unpredicatable.

✅ Correct Answer: 3

In the sublimation of iodine

1. randomness of particles remains unaffected
2. randomness of particles tends to decrease
3. energy of the system tends to increase
4. randomness of particles tends to increase

✅ Correct Answer: 2

Variation of heat of reaction with temperature is given by relation known as

1. vant Hoffs isotherm
2. Vant Hoffs isochore
3. Kirchhoffs equation
4. Born-Lande equation.

✅ Correct Answer: 3