Laws of Thermochemistry
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CHXI06:THERMODYNAMICS

369485 Consider the following reaction:
(i) \(\mathrm{\mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l) ; \Delta H=}\)
\(\rm{-X_{1} \mathrm{kJmol}^{-1}}\)
(ii) \(\mathrm{\mathrm{H}_{2}(g)+\dfrac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-X_{2} \mathrm{kJmol}^{-1}}\)
(iii) \(\mathrm{\mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\rm{\Delta H=-X_{3} \mathrm{kJmol}^{-1}}\)
(iv) \(\mathrm{\mathrm{C}_{2} \mathrm{H}_{2}(g)+\dfrac{5}{2} \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\Delta {\text{H = + }}{{\text{X}}_{\text{4}}}{\mkern 1mu} {\text{k}}{\mkern 1mu} {\text{J}}{\mkern 1mu} {\text{mo}}{{\text{l}}^{{\text{ - 1}}}}\)
Enthalpy of formation of \(\mathrm{\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\) is

1 \(\mathrm{-X_{2} \mathrm{kJmol}^{-1}}\)
2 \(\mathrm{+X_{3} \mathrm{kJmol}^{-1}}\)
3 \(\mathrm{-X_{4} \mathrm{kJmol}^{-1}}\)
4 \(\mathrm{+X_{1} \mathrm{kJmol}^{-1}}\)
CHXI06:THERMODYNAMICS

369486 Given:
\({\text{N}}{{\text{H}}_3}\left( {\text{g}} \right) + 3{\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons {\text{NC}}{{\text{l}}_3}\left( {\text{g}} \right) + 3{\text{HCl}}\left( {\text{g}} \right), - \Delta {{\text{H}}_1}\)
\({{\text{N}}_2}\left( {\text{g}} \right) + 3{{\text{H}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\,; - \Delta {{\text{H}}_2}\)
\({{\text{H}}_2}\left( {\text{g}} \right) + {\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{HCl}}\left( {\text{g}} \right);\Delta {{\text{H}}_3}\)
The heat of formation of \(\mathrm{NCl}_{3(\mathrm{~g})}\) in terms of
\(\Delta \mathrm{H}_{1}, \Delta \mathrm{H}_{2}\) and \(\Delta \mathrm{H}_{3}\) is:

1 \(\Delta \mathrm{H}_{\mathrm{f}}=-\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
2 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
3 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}+\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
4 None of the above
CHXI06:THERMODYNAMICS

369487 Given that
\(\rm{2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})} ; \Delta \mathrm{H}=-787 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{H}_{2(\mathrm{~g})}+\dfrac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{H}_{2} \mathrm{O}_{(l)} ; \Delta \mathrm{H}=-286 \mathrm{~kJ}}\)
\({{\text{C}}_{\text{2}}}{{\text{H}}_{{\text{2}}(\;{\text{g}})}}{\text{ + 2}}\frac{{\text{1}}}{{\text{2}}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}} \to {\text{2C}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}}{\text{ + }}{{\text{H}}_{\text{2}}}{{\text{O}}_{({\text{l}})}};\)
\(\Delta {\text{H =  - 1301}}\;{\text{kJ}}\) Heat of formation of acetylene is

1 \(\mathrm{-1802 \mathrm{~kJ}}\)
2 \(\mathrm{+1802 \mathrm{~kJ}}\)
3 \(\mathrm{-800 \mathrm{~kJ}}\)
4 \(\mathrm{+228 \mathrm{~kJ}}\)
CHXI06:THERMODYNAMICS

369488 \(\mathrm{2 \mathrm{Zn}+\mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO} ; \Delta H^{\circ}=-616 \mathrm{~kJ}}\)
\(\mathrm{2 \mathrm{Zn}+\mathrm{S}_{2} \rightarrow 2 \mathrm{ZnS} ; \Delta H^{\circ}=-293 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{S}_{2}+2 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2} ; \Delta H^{\circ}=-408 \mathrm{~J}}\)
\(\mathrm{\Delta H^{\circ}}\) for the following reaction,
\(\mathrm{2 \mathrm{ZnS}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_{2}}\)

1 \(\mathrm{-731 \mathrm{~kJ}}\)
2 \(\mathrm{-1317 k J}\)
3 \(\mathrm{-501 \mathrm{~kJ}}\)
4 \(\mathrm{+731 \mathrm{~kJ}}\)
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CHXI06:THERMODYNAMICS

369485 Consider the following reaction:
(i) \(\mathrm{\mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l) ; \Delta H=}\)
\(\rm{-X_{1} \mathrm{kJmol}^{-1}}\)
(ii) \(\mathrm{\mathrm{H}_{2}(g)+\dfrac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-X_{2} \mathrm{kJmol}^{-1}}\)
(iii) \(\mathrm{\mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\rm{\Delta H=-X_{3} \mathrm{kJmol}^{-1}}\)
(iv) \(\mathrm{\mathrm{C}_{2} \mathrm{H}_{2}(g)+\dfrac{5}{2} \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\Delta {\text{H = + }}{{\text{X}}_{\text{4}}}{\mkern 1mu} {\text{k}}{\mkern 1mu} {\text{J}}{\mkern 1mu} {\text{mo}}{{\text{l}}^{{\text{ - 1}}}}\)
Enthalpy of formation of \(\mathrm{\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\) is

1 \(\mathrm{-X_{2} \mathrm{kJmol}^{-1}}\)
2 \(\mathrm{+X_{3} \mathrm{kJmol}^{-1}}\)
3 \(\mathrm{-X_{4} \mathrm{kJmol}^{-1}}\)
4 \(\mathrm{+X_{1} \mathrm{kJmol}^{-1}}\)
CHXI06:THERMODYNAMICS

369486 Given:
\({\text{N}}{{\text{H}}_3}\left( {\text{g}} \right) + 3{\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons {\text{NC}}{{\text{l}}_3}\left( {\text{g}} \right) + 3{\text{HCl}}\left( {\text{g}} \right), - \Delta {{\text{H}}_1}\)
\({{\text{N}}_2}\left( {\text{g}} \right) + 3{{\text{H}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\,; - \Delta {{\text{H}}_2}\)
\({{\text{H}}_2}\left( {\text{g}} \right) + {\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{HCl}}\left( {\text{g}} \right);\Delta {{\text{H}}_3}\)
The heat of formation of \(\mathrm{NCl}_{3(\mathrm{~g})}\) in terms of
\(\Delta \mathrm{H}_{1}, \Delta \mathrm{H}_{2}\) and \(\Delta \mathrm{H}_{3}\) is:

1 \(\Delta \mathrm{H}_{\mathrm{f}}=-\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
2 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
3 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}+\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
4 None of the above
CHXI06:THERMODYNAMICS

369487 Given that
\(\rm{2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})} ; \Delta \mathrm{H}=-787 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{H}_{2(\mathrm{~g})}+\dfrac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{H}_{2} \mathrm{O}_{(l)} ; \Delta \mathrm{H}=-286 \mathrm{~kJ}}\)
\({{\text{C}}_{\text{2}}}{{\text{H}}_{{\text{2}}(\;{\text{g}})}}{\text{ + 2}}\frac{{\text{1}}}{{\text{2}}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}} \to {\text{2C}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}}{\text{ + }}{{\text{H}}_{\text{2}}}{{\text{O}}_{({\text{l}})}};\)
\(\Delta {\text{H =  - 1301}}\;{\text{kJ}}\) Heat of formation of acetylene is

1 \(\mathrm{-1802 \mathrm{~kJ}}\)
2 \(\mathrm{+1802 \mathrm{~kJ}}\)
3 \(\mathrm{-800 \mathrm{~kJ}}\)
4 \(\mathrm{+228 \mathrm{~kJ}}\)
CHXI06:THERMODYNAMICS

369488 \(\mathrm{2 \mathrm{Zn}+\mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO} ; \Delta H^{\circ}=-616 \mathrm{~kJ}}\)
\(\mathrm{2 \mathrm{Zn}+\mathrm{S}_{2} \rightarrow 2 \mathrm{ZnS} ; \Delta H^{\circ}=-293 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{S}_{2}+2 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2} ; \Delta H^{\circ}=-408 \mathrm{~J}}\)
\(\mathrm{\Delta H^{\circ}}\) for the following reaction,
\(\mathrm{2 \mathrm{ZnS}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_{2}}\)

1 \(\mathrm{-731 \mathrm{~kJ}}\)
2 \(\mathrm{-1317 k J}\)
3 \(\mathrm{-501 \mathrm{~kJ}}\)
4 \(\mathrm{+731 \mathrm{~kJ}}\)
NEET DIGITAL LIBRARY
CHXI06:THERMODYNAMICS

369485 Consider the following reaction:
(i) \(\mathrm{\mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l) ; \Delta H=}\)
\(\rm{-X_{1} \mathrm{kJmol}^{-1}}\)
(ii) \(\mathrm{\mathrm{H}_{2}(g)+\dfrac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-X_{2} \mathrm{kJmol}^{-1}}\)
(iii) \(\mathrm{\mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\rm{\Delta H=-X_{3} \mathrm{kJmol}^{-1}}\)
(iv) \(\mathrm{\mathrm{C}_{2} \mathrm{H}_{2}(g)+\dfrac{5}{2} \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\Delta {\text{H = + }}{{\text{X}}_{\text{4}}}{\mkern 1mu} {\text{k}}{\mkern 1mu} {\text{J}}{\mkern 1mu} {\text{mo}}{{\text{l}}^{{\text{ - 1}}}}\)
Enthalpy of formation of \(\mathrm{\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\) is

1 \(\mathrm{-X_{2} \mathrm{kJmol}^{-1}}\)
2 \(\mathrm{+X_{3} \mathrm{kJmol}^{-1}}\)
3 \(\mathrm{-X_{4} \mathrm{kJmol}^{-1}}\)
4 \(\mathrm{+X_{1} \mathrm{kJmol}^{-1}}\)
CHXI06:THERMODYNAMICS

369486 Given:
\({\text{N}}{{\text{H}}_3}\left( {\text{g}} \right) + 3{\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons {\text{NC}}{{\text{l}}_3}\left( {\text{g}} \right) + 3{\text{HCl}}\left( {\text{g}} \right), - \Delta {{\text{H}}_1}\)
\({{\text{N}}_2}\left( {\text{g}} \right) + 3{{\text{H}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\,; - \Delta {{\text{H}}_2}\)
\({{\text{H}}_2}\left( {\text{g}} \right) + {\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{HCl}}\left( {\text{g}} \right);\Delta {{\text{H}}_3}\)
The heat of formation of \(\mathrm{NCl}_{3(\mathrm{~g})}\) in terms of
\(\Delta \mathrm{H}_{1}, \Delta \mathrm{H}_{2}\) and \(\Delta \mathrm{H}_{3}\) is:

1 \(\Delta \mathrm{H}_{\mathrm{f}}=-\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
2 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
3 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}+\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
4 None of the above
CHXI06:THERMODYNAMICS

369487 Given that
\(\rm{2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})} ; \Delta \mathrm{H}=-787 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{H}_{2(\mathrm{~g})}+\dfrac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{H}_{2} \mathrm{O}_{(l)} ; \Delta \mathrm{H}=-286 \mathrm{~kJ}}\)
\({{\text{C}}_{\text{2}}}{{\text{H}}_{{\text{2}}(\;{\text{g}})}}{\text{ + 2}}\frac{{\text{1}}}{{\text{2}}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}} \to {\text{2C}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}}{\text{ + }}{{\text{H}}_{\text{2}}}{{\text{O}}_{({\text{l}})}};\)
\(\Delta {\text{H =  - 1301}}\;{\text{kJ}}\) Heat of formation of acetylene is

1 \(\mathrm{-1802 \mathrm{~kJ}}\)
2 \(\mathrm{+1802 \mathrm{~kJ}}\)
3 \(\mathrm{-800 \mathrm{~kJ}}\)
4 \(\mathrm{+228 \mathrm{~kJ}}\)
CHXI06:THERMODYNAMICS

369488 \(\mathrm{2 \mathrm{Zn}+\mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO} ; \Delta H^{\circ}=-616 \mathrm{~kJ}}\)
\(\mathrm{2 \mathrm{Zn}+\mathrm{S}_{2} \rightarrow 2 \mathrm{ZnS} ; \Delta H^{\circ}=-293 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{S}_{2}+2 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2} ; \Delta H^{\circ}=-408 \mathrm{~J}}\)
\(\mathrm{\Delta H^{\circ}}\) for the following reaction,
\(\mathrm{2 \mathrm{ZnS}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_{2}}\)

1 \(\mathrm{-731 \mathrm{~kJ}}\)
2 \(\mathrm{-1317 k J}\)
3 \(\mathrm{-501 \mathrm{~kJ}}\)
4 \(\mathrm{+731 \mathrm{~kJ}}\)
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CHXI06:THERMODYNAMICS

369485 Consider the following reaction:
(i) \(\mathrm{\mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l) ; \Delta H=}\)
\(\rm{-X_{1} \mathrm{kJmol}^{-1}}\)
(ii) \(\mathrm{\mathrm{H}_{2}(g)+\dfrac{1}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}) ; \Delta H=-X_{2} \mathrm{kJmol}^{-1}}\)
(iii) \(\mathrm{\mathrm{CO}_{2}(g)+\mathrm{H}_{2}(g) \rightarrow \mathrm{CO}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\rm{\Delta H=-X_{3} \mathrm{kJmol}^{-1}}\)
(iv) \(\mathrm{\mathrm{C}_{2} \mathrm{H}_{2}(g)+\dfrac{5}{2} \mathrm{O}_{2}(g) \rightarrow 2 \mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\);
\(\Delta {\text{H = + }}{{\text{X}}_{\text{4}}}{\mkern 1mu} {\text{k}}{\mkern 1mu} {\text{J}}{\mkern 1mu} {\text{mo}}{{\text{l}}^{{\text{ - 1}}}}\)
Enthalpy of formation of \(\mathrm{\mathrm{H}_{2} \mathrm{O}(\mathrm{l})}\) is

1 \(\mathrm{-X_{2} \mathrm{kJmol}^{-1}}\)
2 \(\mathrm{+X_{3} \mathrm{kJmol}^{-1}}\)
3 \(\mathrm{-X_{4} \mathrm{kJmol}^{-1}}\)
4 \(\mathrm{+X_{1} \mathrm{kJmol}^{-1}}\)
CHXI06:THERMODYNAMICS

369486 Given:
\({\text{N}}{{\text{H}}_3}\left( {\text{g}} \right) + 3{\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons {\text{NC}}{{\text{l}}_3}\left( {\text{g}} \right) + 3{\text{HCl}}\left( {\text{g}} \right), - \Delta {{\text{H}}_1}\)
\({{\text{N}}_2}\left( {\text{g}} \right) + 3{{\text{H}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\,; - \Delta {{\text{H}}_2}\)
\({{\text{H}}_2}\left( {\text{g}} \right) + {\text{C}}{{\text{l}}_2}\left( {\text{g}} \right) \rightleftharpoons 2{\text{HCl}}\left( {\text{g}} \right);\Delta {{\text{H}}_3}\)
The heat of formation of \(\mathrm{NCl}_{3(\mathrm{~g})}\) in terms of
\(\Delta \mathrm{H}_{1}, \Delta \mathrm{H}_{2}\) and \(\Delta \mathrm{H}_{3}\) is:

1 \(\Delta \mathrm{H}_{\mathrm{f}}=-\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
2 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}-\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
3 \(\Delta \mathrm{H}_{\mathrm{f}}=\Delta \mathrm{H}_{1}+\dfrac{\Delta \mathrm{H}_{2}}{2}+\dfrac{3}{2} \Delta \mathrm{H}_{3}\)
4 None of the above
CHXI06:THERMODYNAMICS

369487 Given that
\(\rm{2 \mathrm{C}_{(\mathrm{s})}+2 \mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{CO}_{2(\mathrm{~g})} ; \Delta \mathrm{H}=-787 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{H}_{2(\mathrm{~g})}+\dfrac{1}{2} \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{H}_{2} \mathrm{O}_{(l)} ; \Delta \mathrm{H}=-286 \mathrm{~kJ}}\)
\({{\text{C}}_{\text{2}}}{{\text{H}}_{{\text{2}}(\;{\text{g}})}}{\text{ + 2}}\frac{{\text{1}}}{{\text{2}}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}} \to {\text{2C}}{{\text{O}}_{{\text{2}}(\;{\text{g}})}}{\text{ + }}{{\text{H}}_{\text{2}}}{{\text{O}}_{({\text{l}})}};\)
\(\Delta {\text{H =  - 1301}}\;{\text{kJ}}\) Heat of formation of acetylene is

1 \(\mathrm{-1802 \mathrm{~kJ}}\)
2 \(\mathrm{+1802 \mathrm{~kJ}}\)
3 \(\mathrm{-800 \mathrm{~kJ}}\)
4 \(\mathrm{+228 \mathrm{~kJ}}\)
CHXI06:THERMODYNAMICS

369488 \(\mathrm{2 \mathrm{Zn}+\mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO} ; \Delta H^{\circ}=-616 \mathrm{~kJ}}\)
\(\mathrm{2 \mathrm{Zn}+\mathrm{S}_{2} \rightarrow 2 \mathrm{ZnS} ; \Delta H^{\circ}=-293 \mathrm{~kJ}}\)
\(\mathrm{\mathrm{S}_{2}+2 \mathrm{O}_{2} \rightarrow 2 \mathrm{SO}_{2} ; \Delta H^{\circ}=-408 \mathrm{~J}}\)
\(\mathrm{\Delta H^{\circ}}\) for the following reaction,
\(\mathrm{2 \mathrm{ZnS}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{ZnO}+2 \mathrm{SO}_{2}}\)

1 \(\mathrm{-731 \mathrm{~kJ}}\)
2 \(\mathrm{-1317 k J}\)
3 \(\mathrm{-501 \mathrm{~kJ}}\)
4 \(\mathrm{+731 \mathrm{~kJ}}\)
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