Q. No.Which of the following statements is/are correct?
1. a and b
2. b, c and d
3. b and c
4. None of the above
| (a) | Heat is a way of transferring energy. |
| (b) | Heat is not a property of the system, whereas temperature is a property of the system. |
| (c) | Reactions that are accompanied by the evolution of heat are called endothermic reactions. |
| (d) | Those reactions in which heat is absorbed are known as exothermic reactions. |
1. a and b
2. b, c and d
3. b and c
4. None of the above
Subtopic: First Law of Thermodynamics | Classification of System, Extensive & Intensive Properties | Thermochemistry |
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Match Column I (Reactions) with Column II (Enthalpy) and mark the appropriate choice:
1. (A) →(iv), (B)→(iii), (C) →(i), (D)→ (ii)
2. (A) →(ii), (B)→(i), (C) →(iv), (D)→ (iii)
3. (A) →(i), (B)→(ii), (C) →(iii), (D)→ (iv)
4. (A) →(iii), (B)→(iv), (C) →(ii), (D)→ (i)
| Column I (Reactions) | Column II (Enthalpy) | ||
| (A) | \(\small{CH_{4(g)} + 2O_{2(g)} \rightarrow CO_{2(g)} + 2H_2O}\) | (i) | \(\Delta _{sol}H^o\) |
| (B) | \( H_{2(g)} \rightarrow 2H_{(g)}\) | (ii) | \(\Delta _{lattice}H^o\) |
| (C) | \(NaCl_{(s)} \rightarrow Na^+_{(g)} + Cl^-_{(g)} \) | (iii) | \(\Delta _{c}H^o\) |
| (D) | \(NaCl_{(s)} \rightarrow Na^+_{(aq)} + Cl^-_{(aq)} \) | (iv) | \(\Delta _{bond}H^o\) |
1. (A) →(iv), (B)→(iii), (C) →(i), (D)→ (ii)
2. (A) →(ii), (B)→(i), (C) →(iv), (D)→ (iii)
3. (A) →(i), (B)→(ii), (C) →(iii), (D)→ (iv)
4. (A) →(iii), (B)→(iv), (C) →(ii), (D)→ (i)
Subtopic: Thermochemistry |
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The enthalpy change for the reaction is called
1. Enthalpy of formation
2. Enthalpy of vaporisation
3. Enthalpy of sublimation
4. Enthalpy of combustion
Subtopic: Thermochemistry |
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Consider a reaction:
\(A_2 + B_2 \rightarrow 2AB\\ (g)~~~~(g)~~~~~~~~(g) \)
If \(\Delta H^o_f \) of \(A_2 , AB \) and \(B_2\) are in the ratio \(1: {1 \over 2}: 1\) and \(\Delta H \) of the reaction is -200 kJ/mol. The value of \(\Delta H^o_f~ (A_2)\)(kJ mol-1) is:
1. 250
2. 200
3. 300
4. 240
\(A_2 + B_2 \rightarrow 2AB\\ (g)~~~~(g)~~~~~~~~(g) \)
If \(\Delta H^o_f \) of \(A_2 , AB \) and \(B_2\) are in the ratio \(1: {1 \over 2}: 1\) and \(\Delta H \) of the reaction is -200 kJ/mol. The value of \(\Delta H^o_f~ (A_2)\)(kJ mol-1) is:
1. 250
2. 200
3. 300
4. 240
Subtopic: Thermochemistry |
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Consider the following reaction:
\(\mathrm{2H_2(g) + O_2(g) \rightarrow 2H_2O(g); ~\Delta_rH^\circ = -483.64~ kJ }\)
What is the enthalpy change (in KJ) for the decomposition of one mole of water?
\(\mathrm{2H_2(g) + O_2(g) \rightarrow 2H_2O(g); ~\Delta_rH^\circ = -483.64~ kJ }\)
What is the enthalpy change (in KJ) for the decomposition of one mole of water?
| 1. | 120.9 | 2. | 241.82 |
| 3. | 18 | 4. | 100 |
Subtopic: Thermochemistry |
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NEET - 2023
Hints
Given the following reaction:
\(\mathrm{C}_2 \mathrm{H}_4(g)+6 \mathrm{~F}_2(g) \rightarrow 2 \mathrm{CF}_4(g)+4 \mathrm{HF}(g)\)
Which species has a standard enthalpy of formation \((\Delta H^{\circ})\) equal to 0?
1. \(\mathrm{C}_2 \mathrm{H}_4\)
2. \(\mathrm{F}_2\)
3. \(\mathrm{CF}_4\)
4. \(\mathrm{HF}\)
\(\mathrm{C}_2 \mathrm{H}_4(g)+6 \mathrm{~F}_2(g) \rightarrow 2 \mathrm{CF}_4(g)+4 \mathrm{HF}(g)\)
Which species has a standard enthalpy of formation \((\Delta H^{\circ})\) equal to 0?
1. \(\mathrm{C}_2 \mathrm{H}_4\)
2. \(\mathrm{F}_2\)
3. \(\mathrm{CF}_4\)
4. \(\mathrm{HF}\)
Subtopic: Thermochemistry |
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The standard heat of combustion of carbon (graphite) to CO₂ is –393.5 kJ mol⁻¹. Calculate the heat released when 15.84 g of CO₂ is formed from carbon (graphite) and oxygen gas:
1. 212.49 kJ2. 141.66 kJ
3. 21.25 kJ
4. 42.5 kJ
Subtopic: Thermochemistry |
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The enthalpy of vaporisation of a liquid is 30 kJ mol–1 and entropy of vaporisation is 75 J mol–1 k–1. What is the boiling point of the liquid at 1 atm?
| 1. | 50 K | 2. | 400 K |
| 3. | 450 K | 4. | 600 K |
Subtopic: Thermochemistry |
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The standard enthalpies of formation of diamond and fullerene are 1.90 kJ mol⁻¹ and 38.1 kJ mol⁻¹, respectively. Calculate the enthalpy change for the conversion of diamond to fullerene:
2. 36.2 kJ mol-1
3. 40 kJ mol-1
4. 57.1 kJ mol-1
Subtopic: Thermochemistry |
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What is the enthalpy change (ΔH) for the reaction represented by the equation, \(\mathrm{OF_2 + H_2O \rightarrow O_2+2HF?}\)
[Given the bond energies of \(\mathrm{O-F, O-H, H-F}\) \(\mathrm {and~O=O}\) as 44, 111, 135, and 119 kcal mol–1, respectively]
[Given the bond energies of \(\mathrm{O-F, O-H, H-F}\) \(\mathrm {and~O=O}\) as 44, 111, 135, and 119 kcal mol–1, respectively]
| 1. | –222 kcal | 2. | –88 kcal |
| 3. | –111 kcal | 4. | –79 kcal |
Subtopic: Thermochemistry |
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