272377
Which of the following condition favour the reduction of a metal oxide to metal?
1 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at low temperature
2 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-\mathrm{ve}$ at low temperature
3 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-$ ve at low temperature
4 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at any temperature
Explanation:
$\Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S}(\Delta \mathrm{G}<0-$ Spontaneous Process) for the reduction of a metal oxide, $\Delta G$ value must be negative and this can only achieved all possibilities of $\Delta H$ and $T \Delta S$ values, when the $\Delta H=-v e$ and $T \Delta S=+v e$ at any temperature.
AIIMS-2012
Thermodynamics
272379
Enthalpy of formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are $-161 \mathrm{~kJ}$ and $-92 \mathrm{~kJ}$ respectively. Which of the following statements is incorrect?
1 $\mathrm{HCl}$ is more stable than $\mathrm{HF}$.
2 $\mathrm{HF}$ and $\mathrm{HCl}$ are exothermic compounds.
3 The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen.
4 $\mathrm{HF}$ is more stable than $\mathrm{HCl}$.
Explanation:
Enthalpy of formation of $\mathrm{HF}$ is more than the Enthalpy of formation of $\mathrm{HCl}$. So, $\mathrm{HF}$ is more stable than $\mathrm{HCl}$. Formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are Exothermic.
AIIMS-2010
Thermodynamics
272389
One mole of an ideal gas for which $\mathrm{C}_{\mathrm{T}}=(3 / 2) R$ is heated reversibly at a constant pressure of 1 atm from $25^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$. The $\Delta \mathrm{H}$ is:
1 $3.75 \mathrm{cal}$
2 $37.5 \mathrm{cal}$
3 $375 \mathrm{cal}$
4 $3725.0 \mathrm{cal}$
Explanation:
We know that, $\Delta \mathrm{H}=\Delta \mathrm{U}+\mathrm{P} \Delta \mathrm{V}$ To find $\Delta \mathrm{U}$ $\Delta \mathrm{U}=\mathrm{C}_{\mathrm{v}} \times\left(\mathrm{T}_2-\mathrm{T}_1\right) \quad$ for 1 mole gas $\Delta \mathrm{U}=\frac{3}{2} \mathrm{R} \times(75)$ Put this value in (i), $\Delta \mathrm{H} =\left(\frac{3}{2} \times \mathrm{R} \times 75\right)+(\mathrm{R} \times 75)$ $\Delta \mathrm{H} =\frac{5}{2} \times \mathrm{R} \times 75$ $\Delta \mathrm{H} =372.56 \mathrm{cal} \quad(\text { Take } \mathrm{R}=1.987 \mathrm{cal})$ $\Delta \mathrm{H} \approx 375 \mathrm{cal}$
AIIMS-2000
Thermodynamics
272395
At a constant volume the specific heat of a gas is 0.075 and its molecular weight is 40 . The gas is:
1 Monoatomic
2 Diatomic
3 Triatomic
4 None of these
Explanation:
Molar heat capacity at constant volume, $\mathrm{C}_{\mathrm{V}}=$ specific heat at constant volume $\times \mathrm{mol}$.wt. $=0.075 \times 40=3.0 \mathrm{cal}$ (Monoatomic $>$ Diatomic) $\because \mathrm{C}_{\mathrm{p}}-\mathrm{C}_{\mathrm{v}}=\mathrm{R}$ or $C_p=\mathrm{R}+\mathrm{C}_{\mathrm{v}}=2+3=5$ Now, $\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_r}=\gamma$ $\therefore \quad \gamma=\frac{5}{3}=1.66$ This value shows that the gas is monoatomic.
NEET Test Series from KOTA - 10 Papers In MS WORD
WhatsApp Here
Thermodynamics
272377
Which of the following condition favour the reduction of a metal oxide to metal?
1 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at low temperature
2 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-\mathrm{ve}$ at low temperature
3 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-$ ve at low temperature
4 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at any temperature
Explanation:
$\Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S}(\Delta \mathrm{G}<0-$ Spontaneous Process) for the reduction of a metal oxide, $\Delta G$ value must be negative and this can only achieved all possibilities of $\Delta H$ and $T \Delta S$ values, when the $\Delta H=-v e$ and $T \Delta S=+v e$ at any temperature.
AIIMS-2012
Thermodynamics
272379
Enthalpy of formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are $-161 \mathrm{~kJ}$ and $-92 \mathrm{~kJ}$ respectively. Which of the following statements is incorrect?
1 $\mathrm{HCl}$ is more stable than $\mathrm{HF}$.
2 $\mathrm{HF}$ and $\mathrm{HCl}$ are exothermic compounds.
3 The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen.
4 $\mathrm{HF}$ is more stable than $\mathrm{HCl}$.
Explanation:
Enthalpy of formation of $\mathrm{HF}$ is more than the Enthalpy of formation of $\mathrm{HCl}$. So, $\mathrm{HF}$ is more stable than $\mathrm{HCl}$. Formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are Exothermic.
AIIMS-2010
Thermodynamics
272389
One mole of an ideal gas for which $\mathrm{C}_{\mathrm{T}}=(3 / 2) R$ is heated reversibly at a constant pressure of 1 atm from $25^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$. The $\Delta \mathrm{H}$ is:
1 $3.75 \mathrm{cal}$
2 $37.5 \mathrm{cal}$
3 $375 \mathrm{cal}$
4 $3725.0 \mathrm{cal}$
Explanation:
We know that, $\Delta \mathrm{H}=\Delta \mathrm{U}+\mathrm{P} \Delta \mathrm{V}$ To find $\Delta \mathrm{U}$ $\Delta \mathrm{U}=\mathrm{C}_{\mathrm{v}} \times\left(\mathrm{T}_2-\mathrm{T}_1\right) \quad$ for 1 mole gas $\Delta \mathrm{U}=\frac{3}{2} \mathrm{R} \times(75)$ Put this value in (i), $\Delta \mathrm{H} =\left(\frac{3}{2} \times \mathrm{R} \times 75\right)+(\mathrm{R} \times 75)$ $\Delta \mathrm{H} =\frac{5}{2} \times \mathrm{R} \times 75$ $\Delta \mathrm{H} =372.56 \mathrm{cal} \quad(\text { Take } \mathrm{R}=1.987 \mathrm{cal})$ $\Delta \mathrm{H} \approx 375 \mathrm{cal}$
AIIMS-2000
Thermodynamics
272395
At a constant volume the specific heat of a gas is 0.075 and its molecular weight is 40 . The gas is:
1 Monoatomic
2 Diatomic
3 Triatomic
4 None of these
Explanation:
Molar heat capacity at constant volume, $\mathrm{C}_{\mathrm{V}}=$ specific heat at constant volume $\times \mathrm{mol}$.wt. $=0.075 \times 40=3.0 \mathrm{cal}$ (Monoatomic $>$ Diatomic) $\because \mathrm{C}_{\mathrm{p}}-\mathrm{C}_{\mathrm{v}}=\mathrm{R}$ or $C_p=\mathrm{R}+\mathrm{C}_{\mathrm{v}}=2+3=5$ Now, $\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_r}=\gamma$ $\therefore \quad \gamma=\frac{5}{3}=1.66$ This value shows that the gas is monoatomic.
272377
Which of the following condition favour the reduction of a metal oxide to metal?
1 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at low temperature
2 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-\mathrm{ve}$ at low temperature
3 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-$ ve at low temperature
4 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at any temperature
Explanation:
$\Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S}(\Delta \mathrm{G}<0-$ Spontaneous Process) for the reduction of a metal oxide, $\Delta G$ value must be negative and this can only achieved all possibilities of $\Delta H$ and $T \Delta S$ values, when the $\Delta H=-v e$ and $T \Delta S=+v e$ at any temperature.
AIIMS-2012
Thermodynamics
272379
Enthalpy of formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are $-161 \mathrm{~kJ}$ and $-92 \mathrm{~kJ}$ respectively. Which of the following statements is incorrect?
1 $\mathrm{HCl}$ is more stable than $\mathrm{HF}$.
2 $\mathrm{HF}$ and $\mathrm{HCl}$ are exothermic compounds.
3 The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen.
4 $\mathrm{HF}$ is more stable than $\mathrm{HCl}$.
Explanation:
Enthalpy of formation of $\mathrm{HF}$ is more than the Enthalpy of formation of $\mathrm{HCl}$. So, $\mathrm{HF}$ is more stable than $\mathrm{HCl}$. Formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are Exothermic.
AIIMS-2010
Thermodynamics
272389
One mole of an ideal gas for which $\mathrm{C}_{\mathrm{T}}=(3 / 2) R$ is heated reversibly at a constant pressure of 1 atm from $25^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$. The $\Delta \mathrm{H}$ is:
1 $3.75 \mathrm{cal}$
2 $37.5 \mathrm{cal}$
3 $375 \mathrm{cal}$
4 $3725.0 \mathrm{cal}$
Explanation:
We know that, $\Delta \mathrm{H}=\Delta \mathrm{U}+\mathrm{P} \Delta \mathrm{V}$ To find $\Delta \mathrm{U}$ $\Delta \mathrm{U}=\mathrm{C}_{\mathrm{v}} \times\left(\mathrm{T}_2-\mathrm{T}_1\right) \quad$ for 1 mole gas $\Delta \mathrm{U}=\frac{3}{2} \mathrm{R} \times(75)$ Put this value in (i), $\Delta \mathrm{H} =\left(\frac{3}{2} \times \mathrm{R} \times 75\right)+(\mathrm{R} \times 75)$ $\Delta \mathrm{H} =\frac{5}{2} \times \mathrm{R} \times 75$ $\Delta \mathrm{H} =372.56 \mathrm{cal} \quad(\text { Take } \mathrm{R}=1.987 \mathrm{cal})$ $\Delta \mathrm{H} \approx 375 \mathrm{cal}$
AIIMS-2000
Thermodynamics
272395
At a constant volume the specific heat of a gas is 0.075 and its molecular weight is 40 . The gas is:
1 Monoatomic
2 Diatomic
3 Triatomic
4 None of these
Explanation:
Molar heat capacity at constant volume, $\mathrm{C}_{\mathrm{V}}=$ specific heat at constant volume $\times \mathrm{mol}$.wt. $=0.075 \times 40=3.0 \mathrm{cal}$ (Monoatomic $>$ Diatomic) $\because \mathrm{C}_{\mathrm{p}}-\mathrm{C}_{\mathrm{v}}=\mathrm{R}$ or $C_p=\mathrm{R}+\mathrm{C}_{\mathrm{v}}=2+3=5$ Now, $\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_r}=\gamma$ $\therefore \quad \gamma=\frac{5}{3}=1.66$ This value shows that the gas is monoatomic.
272377
Which of the following condition favour the reduction of a metal oxide to metal?
1 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at low temperature
2 $\Delta \mathrm{H}=+\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-\mathrm{ve}$ at low temperature
3 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=-$ ve at low temperature
4 $\Delta \mathrm{H}=-\mathrm{ve}, \mathrm{T} \Delta \mathrm{S}=+$ ve at any temperature
Explanation:
$\Delta \mathrm{G}=\Delta \mathrm{H}-\mathrm{T} \Delta \mathrm{S}(\Delta \mathrm{G}<0-$ Spontaneous Process) for the reduction of a metal oxide, $\Delta G$ value must be negative and this can only achieved all possibilities of $\Delta H$ and $T \Delta S$ values, when the $\Delta H=-v e$ and $T \Delta S=+v e$ at any temperature.
AIIMS-2012
Thermodynamics
272379
Enthalpy of formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are $-161 \mathrm{~kJ}$ and $-92 \mathrm{~kJ}$ respectively. Which of the following statements is incorrect?
1 $\mathrm{HCl}$ is more stable than $\mathrm{HF}$.
2 $\mathrm{HF}$ and $\mathrm{HCl}$ are exothermic compounds.
3 The affinity of fluorine to hydrogen is greater than the affinity of chlorine to hydrogen.
4 $\mathrm{HF}$ is more stable than $\mathrm{HCl}$.
Explanation:
Enthalpy of formation of $\mathrm{HF}$ is more than the Enthalpy of formation of $\mathrm{HCl}$. So, $\mathrm{HF}$ is more stable than $\mathrm{HCl}$. Formation of $\mathrm{HF}$ and $\mathrm{HCl}$ are Exothermic.
AIIMS-2010
Thermodynamics
272389
One mole of an ideal gas for which $\mathrm{C}_{\mathrm{T}}=(3 / 2) R$ is heated reversibly at a constant pressure of 1 atm from $25^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$. The $\Delta \mathrm{H}$ is:
1 $3.75 \mathrm{cal}$
2 $37.5 \mathrm{cal}$
3 $375 \mathrm{cal}$
4 $3725.0 \mathrm{cal}$
Explanation:
We know that, $\Delta \mathrm{H}=\Delta \mathrm{U}+\mathrm{P} \Delta \mathrm{V}$ To find $\Delta \mathrm{U}$ $\Delta \mathrm{U}=\mathrm{C}_{\mathrm{v}} \times\left(\mathrm{T}_2-\mathrm{T}_1\right) \quad$ for 1 mole gas $\Delta \mathrm{U}=\frac{3}{2} \mathrm{R} \times(75)$ Put this value in (i), $\Delta \mathrm{H} =\left(\frac{3}{2} \times \mathrm{R} \times 75\right)+(\mathrm{R} \times 75)$ $\Delta \mathrm{H} =\frac{5}{2} \times \mathrm{R} \times 75$ $\Delta \mathrm{H} =372.56 \mathrm{cal} \quad(\text { Take } \mathrm{R}=1.987 \mathrm{cal})$ $\Delta \mathrm{H} \approx 375 \mathrm{cal}$
AIIMS-2000
Thermodynamics
272395
At a constant volume the specific heat of a gas is 0.075 and its molecular weight is 40 . The gas is:
1 Monoatomic
2 Diatomic
3 Triatomic
4 None of these
Explanation:
Molar heat capacity at constant volume, $\mathrm{C}_{\mathrm{V}}=$ specific heat at constant volume $\times \mathrm{mol}$.wt. $=0.075 \times 40=3.0 \mathrm{cal}$ (Monoatomic $>$ Diatomic) $\because \mathrm{C}_{\mathrm{p}}-\mathrm{C}_{\mathrm{v}}=\mathrm{R}$ or $C_p=\mathrm{R}+\mathrm{C}_{\mathrm{v}}=2+3=5$ Now, $\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_r}=\gamma$ $\therefore \quad \gamma=\frac{5}{3}=1.66$ This value shows that the gas is monoatomic.