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Q1. What are the units of molar heat capacity?

• J K^-1 mol^-1
• J K
• J K^-1
• J

Solution

Molar heat capacity is the heat required to raise the temperature of 1 mole of substance by one degree or 1 K.Molar heat capacity = heat absorbed in Joules (J)/Rise in temperature (K) x Molar mass (mol)

Q2. Tea placed in a closed vessel is an example of

• open system
• closed system
• isolated system
• insulated system

Solution

A system which can exchange energy with the surroundings but not mass is called a closed system. When tea is placed in a closed vessel, only energy is exchanged with the surrounding so it is an example of closed system.

Q3. In Born-Haber cycle, the sum of the enthalpy changes around a cycle is

• Zero
• Constant
• Negative integer
• Positive integer

Solution

The Born-Haber cycle, is based on Hess Law or Law of constant heat summation which states that the standard enthalpy of reaction is the sum of algebraic sum of the standard enthalpies of reactions into which the overall reaction may be splitted. So the change in enthalpy around a cycle is zero.

Q4. Which of the following statements is correct about the process of evaporation of water from an open beaker?

• It is a spontaneous and endothermic process.
• It is a spontaneous and exothermic process.
• It is a non-spontaneous and endothermic process.
• It is a non-spontaneous and exothermic process.

Solution

The process of evaporation of water is a spontaneous change because it has a natural tendency to occur either on its own or after proper initiation under the given set of conditions. It is an endothermic process as it takes in heat energy.

Q5. Which of the following is extensive property?

• Entropy
• Specific heat capacity
• Temperature
• Refractive index

Solution

Value of entropy depends upon the amount of the substance present in the system.

Q6. The solubility of fluorides is much less as compared to corresponding chlorides

• because of high ionization energy.
• because of high lattice enthalpy.
• because of low ionization energy.
• because of low lattice enthalpy.

Solution

The solubility of fluorides is much less as compared to corresponding chlorides because of high lattice enthalpy.

Q7. The increasing order of enthalpy of vaporization of NH₃, PH₃, and AsH₃ is

• NH₃, PH₃, AsH₃
• AsH₃, PH₃, NH₃
• NH₃, AsH₃, PH₃
• PH₃, AsH₃, NH₃

Solution

The inter-particle forces are strongest in NH₃ (Hydrogen bonds). In PH₃ and AsH₃ the inter-particle forces are dipole-dipole forces which are relatively stronger in AsH₃^. So the increasing order of vaporization is PH₃, AsH₃, and NH₃ .

Q8. Which of the following relations is correct for an adiabatic process?

• ∆U = q
• P∆V = 0
• ∆q = 0
• q = + w

Solution

Adiabatic system is that where there is no heat exchange between the system and surrounding.

Q9. Which of the following property is NOT an intensive property?

• Temperature
• Viscosity
• Pressure
• Volume

Solution

The properties of the system which are independent of the quantity or size of matter present in it are called intensive properties. For example temperature, pressure, viscosity, specific heat, density etc

Q10. Spontaneous processes proceed:

• Till equilibrium is achieved.
• Till conditions are favorable.
• Till heat is supplied.
• Till reactant is supplied.

Solution

All spontaneous processes proceed till equilibrium is achieved after which no change is observed in the process going on.

Q11. What is the enthalpy called when one mole of compound is formed under standard conditions from one mole of its constituent elements in their standard state?

• Enthalpy of formation
• Enthalpy of combustion
• Enthalpy of bond dissociation
• Enthalpy of phase change

Solution

The enthalpy of formation of a compound is the enthalpy change when one mole of compound is formed under standard conditions from one mole of its constituent elements in their standard state.

Q12. Which of the following is NOT a state function?

• PV
• q + w
• q_rev/T
• q

Solution

The parameter q is not a state function because it is dependent of the path followed by the reaction.

Q13. Evaporation of water is:

• A process in which no heat changes occur.
• A process accompanied by chemical reaction.
• An exothermic change.
• An endothermic change.

Solution

Evaporation occurs when heat is supplied to water.

Q14. Which of the following process is NOT included in phase transformation?

• Vaporization
• Fusion
• Ionisation
• Sublimation

Solution

Phase transformation is the change of state i.e conversion of one state (solid, liquid or gas) to another. So ionisation is not included in phase transformation.

Q15. What happens to the ions, when an ionic compound dissolves in a solvent?

• They leave their ordered position in the crystal lattice and gets hydrated.
• They leave their ordered position in the crystal lattice and doesn't hydrate.
• They doesn't leave their ordered position in the crystal lattice and gets hydrated.
• None of the above.

Solution

When an ionic compound dissolves in a solvent, the ions leave their ordered position in the crystal lattice and get hydrated.

Q16. Born-Haber cycle is used to calculate:

• Lattice enthalpy
• Enthalpy of formation
• Enthalpy of sublimation
• Enthalpy of fusion

Solution

It is impossible to determine lattice enthalpies of a compound directly by experiment so we use Born-Haber cycle to calculate the lattice enthalpy of a compound in various steps.

Q17. The sum of internal energy and pressure-volume work is defined as

• Enthalpy
• Entropy
• Heat capacity
• Free energy

Solution

The sum of internal energy and pressure-volume work of any system under given set of conditions is called enthalpy. H = U + PV

Q18. The difference between Cp and Cv is equal to

• 2 kcal mol^-1
• 1.99 cal
• 8.314 JK^-1mol^-1
• 8.314 ergs K^-1 mol^-1

Solution

Cp - Cv = R = 8.314 JK^-1mol^-1

Q19. On which of the following factors the enthalpy change of a reaction is NOT dependent?

• State of reactants and products
• Nature of reactants and products
• Enthalpy of reactants and products
• Various intermediate reactions

Solution

The enthalpy change of a reaction does not depend upon the various intermediate reactions.

Q20. What is the enthalpy called when one mole of compound reacts completely with excess oxygen under standard conditions?

• Enthalpy of solution
• Enthalpy of atomization
• Lattice enthalpy
• Enthalpy of combustion

Solution

The enthalpy   of combustion (or the heat of combustion) is the enthalpy change when one mole of compound reacts completely with excess oxygen under standard conditions.

Q21. The process in which no exchange of heat takes place between system and surrounding is known as

• Isobaric process
• Adiabatic process
• Isothermal process
• Isochoric process

Solution

In adiabatic process no heat exchange occurs between the system and surroundings.

Q22. Which of the following process does NOT occur during a chemical reaction?

• Rearrangement of atoms
• Collision between molecules
• Formation of new atoms
• Formation of new products from the elements that are not present in the reactants

Solution

In a chemical reation the products are formed from the reactants. So they have the elements which are present in the reactants.

Q23. What is the change in the entropy of water, When ice melts into water?

• Entropy of water decreases.
• Entropy of water increases.
• Entropy of water becomes zero.
• Entropy of water remains same.

Solution

Entropy is a measure of the disorder or randomness of the system. The greater the randomness in a system, greater is its entropy. The randomness is greater in liquid state as compared to solid state so the entropy increases when ice melts into water. 

Q24. Which of the following compounds requires maximum heat to vaporize?

• Water
• Acetone
• Nitrogen
• Hydrochloric acid

Solution

The amount of heat required to vaporize a given compound depends on the intermolecular forces present in the compound. Since water contains strong hydrogen bonds so it requires maximum heat to vaporize.

Q25. Units of entropy change are:

• kJ K^-1
• JK^-1
• JK^-1mol^-1
• K^-1 mol^-1

Solution

As entropy change,  =  

Q26. Heat change of a process in which volume remains constant is given by:

• ∆H
• ∆n
• ∆G
• ∆U

Solution

At constant volume, heat change

Q27. The internal energy of a system is

• Kinetic energy only
• Potential energy only
• Kinetic as well as potential energy
• Unpredictable

Solution

The internal energy of a system is the sum of all the energies i.e mechanical, chemical, potential, kinetic etc present in the system.

Q28. Standard enthalpy of vapourisation ∆_vap H^o for water at 100^oC is 40.66 kJ mol^-1. The internal energy of vaporization of water at 100^oC (in kJmol-1) is:

• +37.56
• -43.76
• +43.76
• +40.66

Solution

H₂O_(l) → H₂O_(g)  ∆H = ∆E + ∆nRT   

Q29. For the reaction Hg (l) ---------> Hg (g) , the entropy change will have the sign:

• Negative
• Positive
• Both positive and negative
• None of the above

Solution

In this reaction, liquid changes to more disordered gaseous state.

Q30. A system absorbs 500 kJ heat and performs 250 kJ work on the surroundings. The increase in internal energy of the system is:

• 750 kJ
• 250 kJ
• 500 kJ
• 1000 kJ

Solution

Change in internal energy = Heat added to the system-work done by the system

Q31. Which of the following is true about a spontaneous process?

• Gibbs energy change is 0.
• Gibbs energy change is less than 0.
• Gibbs energy change is greater than 0.
• Spontaneity does not depend on Gibbs energy.

Solution

The criteria for spontaneity is < 0.

Q32. The enthalpies of fusion for all reactions are

• Positive
• Negative
• Zero
• Depends on the type of substance

Solution

The enthalpies of fusion for all reactions are always positive because melting of a solid is an endothermic process in which heat is supplied to the reaction Hence the sum of enthalpies of the product is greater than the sum of enthalpies of the reactant.

Q33. In the evaporation of water, the entropy

• decreases
• increases
• does not change
• first increases and then decreases

Solution

Entropy is the measure of randomness. If the system is disordered, the randomness increases and consequently entropy increases and vice versa.

Q34. For a spontaneous chemical process, the free energy change is

• positive
• negative
• zero
• not measurable

Solution

According to Gibbs Helmholtz equation , the value of  is negative for a spontaneous process.

Q35. Which of the following is a state function?

• Heat
• Volume
• Pressure
• Internal energy

Solution

The thermodynamic properties whose values depend only upon the initial and final states of the system and are independent of the manner as to how the change is brought about, are called state functions. Example internal energy (U), enthalpy (H), entropy (S) etc

Q36. The enthalpies of all elements in their standard states are

• infinite
• zero
• negative
• positive

Solution

The enthalpies of all elements in their standard states are zero.

Q37. For the reaction, A (g) +2B (g) →  2C (g) +3D(g) the change of enthalpy at 27^oC is 19 kCal. The Value of ΔE is

• 21.2 kcal
• 17.8 kcal
• 18.4 kcal
• 20.6 kcal

Solution

Q38. On increasing the temperature the entropy of the system

• Increases
• Decreases
• Become zero
• None of these

Solution

On increasing the temperature the entropy of the system increases because increase in temperature increases kinetic energy of molecules and so the randomness.

Q39. What is the value of the enthalpy of neutralization for all strong acids and bases?

• -57.1 kJ
• 57.1 kJ
• 1 kJ
• -1 kJ

Solution

The enthalpy of neutralization of all strong acids and strong bases is always constant i.e -57.1 kJ.

Q40. What does term specific heat implies?

• Heat capacity of 1 g of sample
• Heat capacity of 1 mole of sample
• Heat capacity of 1Kg of sample
• Heat capacity of 1000 g of sample