# Class 11th Chemistry – 6 Thermodynamics MCQs

#### An exothermic reaction is the one in which the reacting substances ____.

Correct! Wrong!

An exothermic reaction is the one that is accompanied with the release of energy. So if the energy has to be released, then the product have to be at lower temperatures than the reacting substances.

#### The conditions that will result in the spontaneity of a process are ____.

Correct! Wrong!

For a spontaneous process, ΔG is negative and ΔS is positive. From Gibb's - Helmholtz equation, we know ΔG = ΔH - T ΔS If ΔHis positive, ΔS is positive and T ΔS > ΔH, then ΔG = -ive. So, the process will be spontaneous.

Correct! Wrong!

Without hint.

#### Indentify the correct statement regarding a spontaneous process:

Correct! Wrong!

Spontaneity of reaction depends on tendency to acquire minimum energy state and maximum randomness. For a spontaneous process is an isolated system the change in entropy is positive

#### Internal energy of a is _____________ .

Correct! Wrong!

Internal energy is the sum of all the energies possessed by the system {electronic, nuclear, potential, chemical bond, and kinetic energy (which constitutes translational, rotational and vibrational energy)}

#### If work is done on the gaseous system, then it is the work of____ and is taken as____ by the latest SI convention.

Correct! Wrong!

By convention, work is done on the gaseous system is the work of compression and is taken as positive.

#### Indentify the correct statement regarding entropy.

Correct! Wrong!

Third law of Thermodynamics.

#### Since the enthalpy of elements in their natural state is taken to be zero, the heat of formation of compound ____.

Correct! Wrong!

The heat of formation of compounds may be negative or positive, because it can be an endothermic or exothermic process.

#### An isolated system is that system in which

Correct! Wrong!

Isolated system can not exchange mass or energy.

#### For the reaction X→ Y, the heat content of Y is greater than that of X. The reaction is ____.

Correct! Wrong!

The heat content of Y is greater than that of X implies that there is absorption of heat by the system. Therefore it is an endothermic system.

#### Which of the following is closed system?

Correct! Wrong!

Closed system can exchange energy and not matter with surroundings . Pressure cooker provides closed system.

#### Calorie is equivalent to :

Correct! Wrong!

I calorie = 4.184 joule

#### Evaporation of water is ____.

Correct! Wrong!

Evaporation leads to the absorption of heat to break the hydrogen bonds between the molecules of water in liquid state. Hence, it is an endothermic process.

Correct! Wrong!

Without hint.

#### In which of the following entropy decreases?

Correct! Wrong!

Crystallization of sucrose solution . Entropy is a measure of randomness during the crystallization of sucrose solution liquid state is changing into solid state hence entropy decreases.

#### Of the reactions given, the endothermic reaction is ____.

Correct! Wrong!

Options A, and C are all combustion reactions, and option B is transition from one form to the other. Hence, they are all exothermic reaction. Option D takes in energy. It is the only endothermic reaction.

#### The enthalpy change for an exothermic reaction ____.

Correct! Wrong!

The enthalpy change for an exothermic reaction is always negative while for an endothermic reaction it is always positive.

#### Which of these statements is false?

Correct! Wrong!

Work is a not state function as it depends upon the path followed.

#### According to the third law of thermodynamics which one of the following quantities for a perfectly crystalline solid is zero at absolute zero?

Correct! Wrong!

Entropy states the randomness or disorderness of the system. At absolute zero, the movement of molecules of the system or randomness of the system is zero, hence entropy is also zero.

#### In an isothermal reversible cyclic process, the total energy change in the internal energy is ____

Correct! Wrong!

An reversible isothermal process is carried out at constant temperature. It is given that the process is cyclic. Hence, the total energy will be the forward plus the backward process. The forward process will be positive and the backward will be negative. Hence, the sum total will be zero for a cyclic process.

#### When a solid melts, there is ____.

Correct! Wrong!

When a solid melts, there is an increase in enthalpy. For a solid to melt, heat is absorbed. So, there is an increase in energy. It is an endothermic reaction.

#### According to Hess' Law, the enthalpy change during a chemical reaction depends upon the ____.

Correct! Wrong!

Hess's Law states that the heat evolved or absorbed only depends upon the nature of the reactants and nature of the final products and is independent of the path or the manner by which this change is brought.

#### The relation for free energy change, enthalpy change and entropy change was derived by ____.

Correct! Wrong!

The relation between free energy change, enthalpy change and entropy change was derived by Gibbs.

#### Which is an extensive property of the system?

Correct! Wrong!

Volume depends upon mass. Hence it is extensive property.

Correct! Wrong!

Without hint.

#### Which of the following relationships is correct?

Correct! Wrong!

H = E + PV represents the relationship rightly. Enthalpy or heat content is the energy stored in a substance that can be available in the form of heat. Mathematically, it is given as H = E + PV. It is a state function and an extensive property.

#### Lattice energy for Nail (s) has a ____ value. This explains the high stability of the compound.

Correct! Wrong!

Lattice energy for Nail (s) has a large negative value. This explains the high stability of the compound. More the energy evolved, more will be the stability.

#### The heat of combustion of a substance is :

Correct! Wrong!

Heat of combustion of a substance is always negative as it is the amount of heat evolved (i.e. decrease in enthalpy) when one mole of the substance is completely burnt in air or oxygen.

#### If the heat of combustion of carbon is -94 kJ at 1 atm pressure, then the intrinsic energy of carbon dioxide is ____.

Correct! Wrong!

The intrinsic energy is the internal energy of the substance. Hence, it would be -94 kJ. Thus, if the heat of combustion of carbon is -94 kJ at 1 atm pressure, then the intrinsic energy of carbon dioxide is 94 kJ.

Class 11th Chemistry - 6 Thermodynamics MCQs
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