273024
Find the approximate value of $(\Delta H-\Delta U)$ in $\mathrm{J}$. $\mathrm{mol}^{-1}$, for the formation of $\mathrm{CO}$ from its elements at $298 \mathrm{~K} .\left(\mathrm{R}=8.314 . \mathrm{J} . K^{-1} \cdot \mathrm{mol}^{-1}\right)$
273025
Assertion: For a reaction $2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) ; \Delta \mathrm{H}>\Delta \mathrm{E}$ Reason: Enthalpy change is always greater than internal energy change.
1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Explanation:
$2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g})$ $\begin{aligned} & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\ & \Delta \mathrm{n}_{\mathrm{g}}=4-2=2 \\ & \Delta_1 \mathrm{H}=\Delta \mathrm{E}+2 \mathrm{RT} \\ & \Delta \mathrm{H}>\Delta \mathrm{E} \end{aligned}$ When $\Delta \mathrm{n}_{\mathrm{g}}$ is negative, then enthalpy may be less than internal energy. so, reason is incorrect.
AIIMS-2008
Thermodynamics
273026
$A B, A_2$ and $B_2$ are diatomic molecules. If the bond enthalpies of $A_2, A B$ and $B_2$ are in the ratio 1:1:0.5 and enthalpy of formation of $\mathrm{AB}$ from $A_2$ and $B_2$ is $-100 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the bond energy of $A_2$ :
Bond energy of $\mathrm{A}_2$ be $\mathrm{X}$ then bond energy of $A B$ is also $X$ and bond energy of $B_2$ is $X / 2$ $\begin{aligned} & \mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB} \\ & =\frac{1}{2} \mathrm{~A}_2+\frac{1}{2} \mathrm{~B}_2 \rightarrow \mathrm{AB} \\ & \Delta \mathrm{H}=-100 \mathrm{~kJ} \\ & \mathrm{Or}-100=\left(\frac{\mathrm{X}}{2}+\frac{\mathrm{X}}{4}\right)-\mathrm{X} \\ & \Rightarrow \quad-100=\left(\frac{2 \mathrm{X}+\mathrm{X}}{4}\right)-\mathrm{X} \\ & -100=\frac{2 \mathrm{X}+\mathrm{X}-4 \mathrm{X}}{4} \\ & \mathrm{X}=400 \mathrm{~kJ} \end{aligned}$
AIIMS-2012
Thermodynamics
273027
Given that $\Delta H_f(H)=218 \mathrm{~kJ} / \mathrm{mol}$, express the $\mathrm{H}-\mathrm{H}$ bond energy in $\mathrm{kcal} / \mathrm{mol}$.
273024
Find the approximate value of $(\Delta H-\Delta U)$ in $\mathrm{J}$. $\mathrm{mol}^{-1}$, for the formation of $\mathrm{CO}$ from its elements at $298 \mathrm{~K} .\left(\mathrm{R}=8.314 . \mathrm{J} . K^{-1} \cdot \mathrm{mol}^{-1}\right)$
273025
Assertion: For a reaction $2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) ; \Delta \mathrm{H}>\Delta \mathrm{E}$ Reason: Enthalpy change is always greater than internal energy change.
1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Explanation:
$2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g})$ $\begin{aligned} & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\ & \Delta \mathrm{n}_{\mathrm{g}}=4-2=2 \\ & \Delta_1 \mathrm{H}=\Delta \mathrm{E}+2 \mathrm{RT} \\ & \Delta \mathrm{H}>\Delta \mathrm{E} \end{aligned}$ When $\Delta \mathrm{n}_{\mathrm{g}}$ is negative, then enthalpy may be less than internal energy. so, reason is incorrect.
AIIMS-2008
Thermodynamics
273026
$A B, A_2$ and $B_2$ are diatomic molecules. If the bond enthalpies of $A_2, A B$ and $B_2$ are in the ratio 1:1:0.5 and enthalpy of formation of $\mathrm{AB}$ from $A_2$ and $B_2$ is $-100 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the bond energy of $A_2$ :
Bond energy of $\mathrm{A}_2$ be $\mathrm{X}$ then bond energy of $A B$ is also $X$ and bond energy of $B_2$ is $X / 2$ $\begin{aligned} & \mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB} \\ & =\frac{1}{2} \mathrm{~A}_2+\frac{1}{2} \mathrm{~B}_2 \rightarrow \mathrm{AB} \\ & \Delta \mathrm{H}=-100 \mathrm{~kJ} \\ & \mathrm{Or}-100=\left(\frac{\mathrm{X}}{2}+\frac{\mathrm{X}}{4}\right)-\mathrm{X} \\ & \Rightarrow \quad-100=\left(\frac{2 \mathrm{X}+\mathrm{X}}{4}\right)-\mathrm{X} \\ & -100=\frac{2 \mathrm{X}+\mathrm{X}-4 \mathrm{X}}{4} \\ & \mathrm{X}=400 \mathrm{~kJ} \end{aligned}$
AIIMS-2012
Thermodynamics
273027
Given that $\Delta H_f(H)=218 \mathrm{~kJ} / \mathrm{mol}$, express the $\mathrm{H}-\mathrm{H}$ bond energy in $\mathrm{kcal} / \mathrm{mol}$.
273024
Find the approximate value of $(\Delta H-\Delta U)$ in $\mathrm{J}$. $\mathrm{mol}^{-1}$, for the formation of $\mathrm{CO}$ from its elements at $298 \mathrm{~K} .\left(\mathrm{R}=8.314 . \mathrm{J} . K^{-1} \cdot \mathrm{mol}^{-1}\right)$
273025
Assertion: For a reaction $2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) ; \Delta \mathrm{H}>\Delta \mathrm{E}$ Reason: Enthalpy change is always greater than internal energy change.
1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Explanation:
$2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g})$ $\begin{aligned} & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\ & \Delta \mathrm{n}_{\mathrm{g}}=4-2=2 \\ & \Delta_1 \mathrm{H}=\Delta \mathrm{E}+2 \mathrm{RT} \\ & \Delta \mathrm{H}>\Delta \mathrm{E} \end{aligned}$ When $\Delta \mathrm{n}_{\mathrm{g}}$ is negative, then enthalpy may be less than internal energy. so, reason is incorrect.
AIIMS-2008
Thermodynamics
273026
$A B, A_2$ and $B_2$ are diatomic molecules. If the bond enthalpies of $A_2, A B$ and $B_2$ are in the ratio 1:1:0.5 and enthalpy of formation of $\mathrm{AB}$ from $A_2$ and $B_2$ is $-100 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the bond energy of $A_2$ :
Bond energy of $\mathrm{A}_2$ be $\mathrm{X}$ then bond energy of $A B$ is also $X$ and bond energy of $B_2$ is $X / 2$ $\begin{aligned} & \mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB} \\ & =\frac{1}{2} \mathrm{~A}_2+\frac{1}{2} \mathrm{~B}_2 \rightarrow \mathrm{AB} \\ & \Delta \mathrm{H}=-100 \mathrm{~kJ} \\ & \mathrm{Or}-100=\left(\frac{\mathrm{X}}{2}+\frac{\mathrm{X}}{4}\right)-\mathrm{X} \\ & \Rightarrow \quad-100=\left(\frac{2 \mathrm{X}+\mathrm{X}}{4}\right)-\mathrm{X} \\ & -100=\frac{2 \mathrm{X}+\mathrm{X}-4 \mathrm{X}}{4} \\ & \mathrm{X}=400 \mathrm{~kJ} \end{aligned}$
AIIMS-2012
Thermodynamics
273027
Given that $\Delta H_f(H)=218 \mathrm{~kJ} / \mathrm{mol}$, express the $\mathrm{H}-\mathrm{H}$ bond energy in $\mathrm{kcal} / \mathrm{mol}$.
273024
Find the approximate value of $(\Delta H-\Delta U)$ in $\mathrm{J}$. $\mathrm{mol}^{-1}$, for the formation of $\mathrm{CO}$ from its elements at $298 \mathrm{~K} .\left(\mathrm{R}=8.314 . \mathrm{J} . K^{-1} \cdot \mathrm{mol}^{-1}\right)$
273025
Assertion: For a reaction $2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g}) ; \Delta \mathrm{H}>\Delta \mathrm{E}$ Reason: Enthalpy change is always greater than internal energy change.
1 If both Assertion and Reason are correct and the Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Explanation:
$2 \mathrm{NH}_3(\mathrm{~g}) \rightarrow \mathrm{N}_2(\mathrm{~g})+3 \mathrm{H}_2(\mathrm{~g})$ $\begin{aligned} & \Delta \mathrm{H}=\Delta \mathrm{E}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\ & \Delta \mathrm{n}_{\mathrm{g}}=4-2=2 \\ & \Delta_1 \mathrm{H}=\Delta \mathrm{E}+2 \mathrm{RT} \\ & \Delta \mathrm{H}>\Delta \mathrm{E} \end{aligned}$ When $\Delta \mathrm{n}_{\mathrm{g}}$ is negative, then enthalpy may be less than internal energy. so, reason is incorrect.
AIIMS-2008
Thermodynamics
273026
$A B, A_2$ and $B_2$ are diatomic molecules. If the bond enthalpies of $A_2, A B$ and $B_2$ are in the ratio 1:1:0.5 and enthalpy of formation of $\mathrm{AB}$ from $A_2$ and $B_2$ is $-100 \mathrm{~kJ} \mathrm{~mol}^{-1}$. What is the bond energy of $A_2$ :
Bond energy of $\mathrm{A}_2$ be $\mathrm{X}$ then bond energy of $A B$ is also $X$ and bond energy of $B_2$ is $X / 2$ $\begin{aligned} & \mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB} \\ & =\frac{1}{2} \mathrm{~A}_2+\frac{1}{2} \mathrm{~B}_2 \rightarrow \mathrm{AB} \\ & \Delta \mathrm{H}=-100 \mathrm{~kJ} \\ & \mathrm{Or}-100=\left(\frac{\mathrm{X}}{2}+\frac{\mathrm{X}}{4}\right)-\mathrm{X} \\ & \Rightarrow \quad-100=\left(\frac{2 \mathrm{X}+\mathrm{X}}{4}\right)-\mathrm{X} \\ & -100=\frac{2 \mathrm{X}+\mathrm{X}-4 \mathrm{X}}{4} \\ & \mathrm{X}=400 \mathrm{~kJ} \end{aligned}$
AIIMS-2012
Thermodynamics
273027
Given that $\Delta H_f(H)=218 \mathrm{~kJ} / \mathrm{mol}$, express the $\mathrm{H}-\mathrm{H}$ bond energy in $\mathrm{kcal} / \mathrm{mol}$.
