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JEE CHEMISTRY MCQ: THERMODYNAMICS

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Application +4 | -1
Assign the sign of work done (based on SI convention) in
the following chemical changes taking place against
external atmospheric pressure
I. N2(g)+3H2(g)⟶2NH3(g)\mathrm{N}_2(g)+3 \mathrm{H}_2(g) \longrightarrow 2 \mathrm{NH}_3(g)

II. NH4HS(s)⟶NH3(g)+H2 S(g)\mathrm{NH}_4 \mathrm{HS}(s) \longrightarrow \mathrm{NH}_3(g)+\mathrm{H}_2 \mathrm{~S}(g)

III. C(s)+CO2(g)⟶2CO(g)\mathrm{C}(\mathrm{s})+\mathrm{CO}_2(g) \longrightarrow 2 \mathrm{CO}(g)

IV. C2H6(g)+3.5O2(g)⟶2CO2(g)+3H2O(l)\mathrm{C}_2 \mathrm{H}_6(g)+3.5 \mathrm{O}_2(g) \longrightarrow 2 \mathrm{CO}_2(g)+3 \mathrm{H}_2 \mathrm{O}(l)
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Correct option: A
IIIIIIIV+−−+\begin{array}{cccccccccccccccccccc} {\text{I}}&{{\text{II}}}&{{\text{III}}}&{{\text{IV}}} \\ + & - & - & + \end{array}
Option A (+, -, -, +) is correct because it correctly assigns the sign of work based on the change in the number of moles of gas (Δng\Delta n_g).

More Questions from THERMODYNAMICS

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Consider following reactions
I:  C(s)+12O2( g)−CO(g),ΔH1=a\ \mathrm{C}(\mathrm{s})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g})-\mathrm{CO}(\mathrm{g}), \Delta \mathrm{H}_1=\mathrm{a}

II: CO(g)+12O2( g)−CO2( g),ΔH2=b\mathrm{CO}(\mathrm{g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g})-\mathrm{CO}_2(\mathrm{~g}), \Delta \mathrm{H}_2=\mathrm{b}

III: C(s)+CO2( g)−2CO(g);ΔH3=c\mathrm{C}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})-2 \mathrm{CO}(\mathrm{g}) ; \Delta \mathrm{H}_3=\mathrm{c}
Select the correct statement
When 0.18 g0.18 \mathrm{~g} of glucose was burnt in a bomb calorimeter, the temperature rose by 4 K.4 \mathrm{~K}. The heat capacity of the calorimeter system is (ΔCH∘=−2.8×106 J/mol glucose)\left(\Delta_{\mathrm{C}} \text{H}^{\circ}=-2.8\times 10^6 \mathrm{~J} / \mathrm{mol} \text{ glucose}\right) Statement-1: CsI{CsI} is less soluble in water compared to CsCl{CsCl}
Satement-2: More amount of heat is liberated during the formation of CsCl{CsCl} than the formation CsI{Cs} I from their elements
Consider the following processes :

ΔH(KJ/mol)1/2A→B+1503B→2C+D−125E+A→2D+350\begin{array}{cccccccccccccccccccc} {}&{\Delta H(KJ/mol)} \\ {1/2A \to B}&{ + 150} \\ {3B \to 2C + D}&{ - 125} \\ {E + A \to 2D}&{ + 350} \end{array}

For B+D→E+2C,ΔH{B}+{D} \rightarrow {E}+2 {C}, \Delta {H} will be :
The difference b/w ΔH\Delta H and Δu\Delta u at constant volume is equal to The heat evolved in the combustion of methane is given by the following equations CH4(g)+2O2(g)→CO2(g)+H2O(l);ΔH=−890.3kJ\mathrm{C}{\mathrm{H}_4}\left( \mathrm{g} \right) + 2{\mathrm{O}_2}\left( \mathrm{g} \right) \to \mathrm{C}{\mathrm{O}_2}\left( \mathrm{g} \right) + {\mathrm{H}_2}\mathrm{O}\left( l \right);\Delta H = - 890.3\mathrm{kJ} How many grams of methane would be required to produce 44.15 kJ of heat of combustion?
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