JEE Main 2022 · 25 Jun · Shift 2 · Chemistry Q62

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ChemistrySingle correct+4 / -1Question 62 of 90

At 25°C and 1 atm pressure, the enthalpy of combustion of benzene (l) and acetylene (g) are $-3268\ \mathrm{kJ\,mol^{-1}}$ and $-1300\ \mathrm{kJ\,mol^{-1}}$ , respectively. The change in enthalpy for the reaction $\mathrm{3C_2H_2(g)\rightarrow C_6H_6(l)}$ , is

+324\ \mathrm{kJ\,mol^{-1}}

+632\ \mathrm{kJ\,mol^{-1}}

-632\ \mathrm{kJ\,mol^{-1}}

-732\ \mathrm{kJ\,mol^{-1}}

Answer and worked solution

Official answer: C

Hess's law. $\Delta H=3\Delta_cH(\mathrm{C_2H_2})-\Delta_cH(\mathrm{C_6H_6})=3(-1300)-(-3268)=-632$ kJ mol $^{-1}$ .

(C)

Topics:Hess's law and enthalpies of reaction

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JEE Main 2022 · 25 Jun · Shift 2, Chemistry question 62