Third Law of Thermodynamics

Q.

The efficiency of fuel cell is given by the expression, $∆\mathrm{H}$ is______

Q.

According to third law of Thermodynamics, "At absolute zero, the entropy of a perfectly crystalline substance is taken as zero”.

1. True

2. False

Q.

What is the temperature in a vacuum?

Q. Which law of thermodynamics help in calculating the absolute value of entropy at different temperatures ?

1. First law
2. Second law
3. Third law
4. Zeroth law

Q. What is the entropy of an ideal crystal at absolute zero, according to the 3rd law of thermodynamics?

1. There is no way to know.
2. 1
3. 0
4. Infinity

Q. What is the entropy of an ideal crystal at absolute zero, according to the 3rd law of thermodynamics?

1. There is no way to know.
2. Infinity
3. 1
4. \N

Q. Entropy of a crystalline solid decrease, when the temperature is raised from 0K to 300K

1. True

2. False

Q.

The entropy of a pure crystal is zero at absolute zero. This is statement of

1. first law of thermodynamics

2. second law of thermodynamics

3. third law of thermodynamics

4. none of these

Q. For a Chemical Process at constant temperature and pressure, $\Delta H$ is Equal to

1. (q/t )(rev)

2. ∆S-T∆G

3. ∆U+P∆V

4. ∆U-P∆V

Q. Calculate the entropy$(J{K}^{-1}$ mol${}^{-1})$ change for the following reversible process:
$\alpha -Tin\rightleftharpoons \beta -Tin$ at ${13}^{\circ }C$
1 mol at 1 atm
$\Delta H_{\text{trans}}=2288J$ mol${}^{-1}$

1. 8
2. 5
3. 0
4. 10

Q. Define the following terms :

(i) Fuel cell

(ii) Limiting molar conductivity $\left({\wedge }_m^0\right)$

Q.

Is isolated system and adiabatic system the same ?

Q.

Calculate the entropy change accompanying the following change of state

$5mol$ of $O_2({27}^{\circ }C,1atm)\to 5mol$ of $O_2({117}^{\circ }C,5atm)$

$C_P$ for $O_2=6.95calde{g}^{-1}mo{l}^{-1}$

1. -8.88 cal deg^-1

2. -6.88 cal deg^-1

3. -9.77 cal deg^-1

4. -10.77 cal deg^-1

Q.

1.0mole of dinitrogen gas at STP condition was put into a vessel of volume 0.025m cube maintained at the temperature of 50degree c. What is the pressure of the gas in the vessel

Q. State third law of thermodynamics.

Q. The entropy change will be positive for which reaction?

1. $H_2\left(g\right)+I_2\left(g\right)\rightleftharpoons 2HI\left(g\right)$
2. $HCl\left(g\right)+N{H}_3\left(g\right)\rightleftharpoons N{H}_{4}Cl\left(s\right)$
3. $N{H}_{4}N{O}_3\left(s\right)\rightleftharpoons N_{2}O\left(g\right)+2H_{2}O\left(g\right)$
4. $MgO\left(s\right)+H_2\left(g\right)\rightleftharpoons Mg\left(s\right)+H_{2}O\left(l\right)$

Q. State third law of thermodynamics. Give 'two' uses.

Q. explain the third law of thermodynamics?

Q.

Paragraph for below question

नीचे दिये गये प्रश्न के लिए अनुच्छेद

The standard enthalpy change for the formation of one mole of a compound from its elements in their most stable states of aggregation (also known as reference states) is called standard molar enthalpy of formation (${\Delta }_f{H}^{\ominus }$). Enthalpy of reaction can be calculated in terms of enthalpy of formation of the reactants and the products of the reaction.

अपने समूहन की सर्वाधिक स्थायी अवस्थाओं (संदर्भ अवस्थाएं भी कहलाती हैं) में अपने तत्वों से एक मोल यौगिक के निर्माण के लिए मानक एन्थैल्पी परिवर्तन मानक मोलर संभवन एन्थैल्पी (${\Delta }_f{H}^{\ominus }$) कहलाती है। अभिक्रिया की एन्थैल्पी की गणना अभिक्रिया के अभिकारकों व उत्पादों की संभवन एन्थैल्पी के पदों में की जा सकती है।

Q. Enthalpy change for which of the following reaction corresponds to standard enthalpy of formation of CO gas?

प्रश्न - निम्नलिखित में से किस अभिक्रिया के लिए एन्थैल्पी परिवर्तन CO गैस की मानक संभवन एन्थैल्पी के संगत है?

1. 2C_(Graphite) + O₂(g) → 2CO(g)
   
   2C_{(ग्रेफाइट)} + O₂(g) → 2CO(g)
2. $C_{\left(Diamond\right)}+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
   
   2C_{(हीरा)} $+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
3. $C_{\left(Graphite\right)}+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
   
   C_{(ग्रेफाइट)} $+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
4. 2C_(Diamond) + O₂(g) → 2CO(g)
   
   2C_{(हीरा)} + O₂(g) → 2CO(g)

Q. There are many substance for example, CO, NO etc, do not follow third law of thermodynamics because

1. These substances are polar
2. These substance do not form crystal at absolute zero temperature
3. These substance follow the second law of thermodynamics
4. These substances do not fulfill the perfectly ordered arrangement at absolute zero

Q.

In terms of Charle’s law explain why -273°C is the lowest possible temperature?

Q. Which of the following processes takes place with decrease of entropy?

1. $Solid\to gas$
2. $sugar+water\to solution$
3. $N{H}_{3\left(g\right)}+HC{l}_{\left(g\right)}\to N{H}_{4}C{l}_{\left(s\right)}$
4. $A_{\left(g\right)}+B_{\left(g\right)}\to mixture$

Q. "For a perfectly crystalline substance at absolute zero, the entropy is zero."

1. Third law
2. Zero law
3. Second law
4. None of these

Q. The third law of thermodynamics is concerned with the :

1. energy transfer
2. direction of energy transfer
3. value of absolute entropy
4. none of these

Q.

For a perfectly crystalline solid $V_{p,m}=a{T}^3+bT$, where $a$ and $b$ are constants. If $C_{p,m}$ is $0.40J/K$ nike at $10K$ and $092J/K$ mole at $20K$, then molar entropy at $20K$ is:

1. 0.92 J/K mol

2. 8.66 J/K mol

3. 0.913 J/K mol

4. None of these

Q. The entropy change in the fusion of 1 mole of a solid melting at ${27}^{0}C$ (Latent heat of fusion, 2930J mo$l^{-1}$)is :

1. 10.73$J{K}^{-1}{mol}^1$
2. 9.77$J{K}^{-1}{mol}^1$
3. 2930$J{K}^{-1}{mol}^1$
4. 108.5$J{K}^{-1}{mol}^1$

Q.

What is the meaning of following line: in crystalline solids same physical property is found to be different along different direction

Q. Give reasons :
The entropy of steam is more than that of water at its boiling point.

Q. The entropy of a crystalline substance at absolute zero on the basis of third law of thermodynamics should be taken as:

1. different for different substances
2. $50$
3. zero
4. $100$

Q. Which of the following is not a state function?

निम्नलिखित में से कौनसा एक अवस्था फलन नहीं है?

1. H – TS
2. U + PV
3. q
4. S