Chemical Thermodynamics · JEE Main previous year questions

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2023 19 questions

Q612023 · 13 Apr 2023 · Shift 2
What happens when methane undergoes combustion in systems A (Adiabatic system) and B (Diathermic container) respectively?
1. A.System A: Temperature falls; System B: Temperature rises
2. B.System A: Temperature rises; System B: Temperature remains same
3. C.System A: Temperature falls; System B: Temperature remains same
4. D.System A: Temperature remains same; System B: Temperature rises
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Answer: B
Q762023 · 13 Apr 2023 · Shift 2
Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Isotopes of hydrogen have almost same chemical properties, but difference in their rates of reaction. Reason R : Isotopes of hydrogen have different enthalpy of bond dissociation. In the light of the above statements, choose the most appropriate answer from the options given below:
1. A.A is not correct but R is correct
2. B.Both A and R are correct but R is NOT the correct explanation of A
3. C.A is correct but R is not correct
4. D.Both A and R are correct and R is the correct explanation of A
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Answer: D
Q802023 · 13 Apr 2023 · Shift 2
Identify the correct order of standard enthalpy of formation of sodium halides :
1. A. $NaI < NaBr < NaCl < NaF$
2. B. $NaI < NaBr < NaF < NaCl$
3. C. $NaF < NaCl < NaBr < NaI$
4. D. $NaCl < NaF < NaBr < NaI$
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Answer: A
Q892023 · 12 Apr 2023 · Shift 1· Numerical answer
One mole of an ideal gas at $350 K$ is in a $2.0 L$ vessel of thermally conducting walls, which are in contact with the surroundings. It undergoes isothermal reversible expansion from $2.0 L$ to $3.0 L$ against a constant pressure of $4 atm$ . The change in entropy of the surroundings ( $Δ S$ ) is _________ $JK^{- 1}$ (Nearest integer) Given: $R = 8.314 J K^{- 1} mol^{- 1}$ .
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Answer: 3
Q662023 · 11 Apr 2023 · Shift 1
For elements $B, C, N, Li, Be, O$ and $F$ , the correct order of first ionization enthalpy is
1. A. $Li < Be < B < C < O < N < F$
2. B. $B > Li > Be > C > N > O > F$
3. C. $Li < Be < B < C < N < O < F$
4. D. $Li < B < Be < C < O < N < F$
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Answer: D
Q722023 · 10 Apr 2023 · Shift 2
1. A.At $60 0^{\circ} C$ , C can reduce FeO
2. B.At $60 0^{\circ} C$ , C can reduce ZnO
3. C.At $60 0^{\circ} C$ , CO can reduce ZnO
4. D.At $60 0^{\circ} C$ , CO cannot reduce FeO
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Answer: A
Q872023 · 10 Apr 2023 · Shift 2· Numerical answer
The number of endothermic process/es from the following is _________. A. $I_{2} (g) \to 2 I (g)$ B. $HCl (g) \to H (g) + Cl (g)$ C. $H_{2} O (l) \to H_{2} O (g)$ D. $C (s) + O_{2} (g) \to CO_{2} (g)$ E. Dissolution of ammonium chloride in water
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Answer: 4
Q852023 · 8 Apr 2023 · Shift 1· Numerical answer
When a $60 W$ electric heater is immersed in a gas for $100 s$ in a constant volume container with adiabatic walls, the temperature of the gas rises by $5^{\circ} C$ . The heat capacity of the given gas is ___________ $J K^{- 1}$ (Nearest integer)
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Answer: 1200
Q842023 · 6 Apr 2023 · Shift 1· Numerical answer
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Answer: 2
Q772023 · 6 Apr 2023 · Shift 2
Ion having highest hydration enthalpy among the given alkaline earth metal ions is :
1. A. $S r^{2 +}$
2. B. $C a^{2 +}$
3. C. $B e^{2 +}$
4. D. $B a^{2 +}$
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Answer: C
Q832023 · 6 Apr 2023 · Shift 2· Numerical answer
Consider the following data $Heat of combustion of H_{2} (g) = - 241.8 kJ mol^{- 1} Heat of combustion of C (s) = - 393.5 kJ mol^{- 1} Heat of combustion of C_{2} H_{5} OH (l) = - 1234.7 kJ mol^{- 1}$ The heat of formation of $C_{2} H_{5} OH (l)$ is $(-)$ ___________ $kJ mol^{- 1}$ (Nearest integer).
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Answer: 278
Q852023 · 1 Feb 2023 · Shift 1· Numerical answer
At $2 5^{\circ} C$ , the enthalpy of the following processes are given : | Reaction | Enthalpy | | :--- | :--- | | $H_{2} (g) + O_{2} (g) \to 2 OH (g)$ | $Δ H^{\circ} = 78 kJ mol^{- 1}$ | | $H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (g)$ | $Δ H^{\circ} = - 242 kJ mol^{- 1}$ | | $H_{2} (g) \to 2 H (g)$ | $Δ H^{\circ} = 436 kJ mol^{- 1}$ | | $\frac{1}{2} O_{2} (g) \to O (g)$ | $Δ H^{\circ} = 249 kJ mol^{- 1}$ | What would be the value of X for the following reaction ? ________ (Nearest integer) $H_{2} O (g) \to H (g) + OH (g) Δ H^{\circ} = X kJ mol^{- 1}$
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Answer: 499
Q832023 · 31 Jan 2023 · Shift 1· Numerical answer
The enthalpy change for the conversion of $\frac{1}{2} Cl_{2} (g)$ to $Cl^{-} (aq)$ is $(-)$ ___________ $kJmol^{- 1}$ (Nearest integer) Given : $Δ_{dis} H_{Cl_{2 (g)}}^{⊖} = 240 kJ mol^{- 1}$ , $Δ_{eg} H_{Cl_{(g)}}^{⊖} = - 350 kJ mol^{- 1}$ , $Δ_{hyd} H_{Cl_{(g)}^{-}}^{⊖} = - 380 kJ mol^{- 1}$
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Answer: 610
Q842023 · 31 Jan 2023 · Shift 2· Numerical answer
Enthalpies of formation of $CCl_{4} (g), H_{2} O (g), CO_{2} (g)$ and $HCl (g)$ are $- 105, - 242, - 394$ and $- 92 kJ mol^{- 1}$ respectively. The magnitude of enthalpy of the reaction given below is ___________ $kJ mol^{- 1}$ . (nearest integer) $CCl_{4} (g) + 2 H_{2} O (g) \to CO_{2} (g) + 4 HCl (g)$
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Answer: 173
Q902023 · 31 Jan 2023 · Shift 2· Numerical answer
The number of alkali metal(s), from $Li, K, Cs, Rb$ having ionization enthalpy greater than $400 kJ mol^{- 1}$ and forming stable super oxide is ___________.
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Answer: 2
Q652023 · 29 Jan 2023 · Shift 1
The bond dissociation energy is highest for
1. A. $C l_{2}$
2. B. $I_{2}$
3. C. $B r_{2}$
4. D. $F_{2}$
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Answer: A
Q612023 · 25 Jan 2023 · Shift 1
Inert gases have positive electron gain enthalpy. Its correct order is :
1. A.He < Ne < Kr < Xe
2. B.He < Xe < Kr < Ne
3. C.Xe < Kr < Ne < He
4. D.He < Kr < Xe < Ne
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Answer: B
Q902023 · 25 Jan 2023 · Shift 2· Numerical answer
The number of incorrect statement/s from the following is/are ____ A. Water vapours are adsorbed by anhydrous calcium chloride. B. There is a decrease in surface energy during adsorption. C. As the adsorption proceeds, $Δ$ H becomes more and more negative. D. Adsorption is accompanied by decrease in entropy of the system.
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Answer: 2
Q812023 · 24 Jan 2023 · Shift 1· Numerical answer
For independent processes at $300 K$ $Process A B C D Δ H / kJ mo l^{- 1} - 25 - 22 2522 Δ S / J K^{- 1} - 80 40 - 50 20$ The number of non-spontaneous processes from the following is ____
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Answer: 2