NEET UG CHEMISTRY MCQ: THERMODYNAMICS

1 Hard

1 of 1

Application +4 | -1

If enthalpies of formation for

\mathrm{C}_2 \mathrm{H}_4(\mathrm{g}), \mathrm{CO}_2(\mathrm{g})

and

\mathrm{H}_2 \mathrm{O}({l})

25^{\circ} \mathrm{C}

and

1 \mathrm{~atm}

pressure are

52,-394

and

-286 \mathrm{~kJ} / \mathrm{mol}

respectively, then enthalpy of combustion of

\mathrm{C}_2 \mathrm{H}_4(\mathrm{g})

will be

View answer and explanation

Correct option: D

-1412 \mathrm{~kJ} / \mathrm{mol}

Option D (-1412 kJ/mol) is correct because the enthalpy of combustion is calculated by subtracting the sum of the enthalpies of formation of the reactants from the sum of the enthalpies of formation of the products, considering stoichiometric coefficients.

More Questions from THERMODYNAMICS

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The internal energy of one mole of a gas is: An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If

{T_i}

is the initial temperature and

{T_f}

is the final temperature, which of the following statements is correct? For which of the process, ∆S is negative? The work done by a weightless piston in causing an expansion ∆V (at constant temperature), when the opposing pressure, P is variable, is given by: Assertion :- At constant pressure of the change

\mathrm{H}_2 \mathrm{O}(\mathrm{s}) \rightarrow \mathrm{H}_2 \mathrm{O}(\mathrm{g})

work done is negative.

Reason :- During phase transition work done is always negative. For the reaction,

\mathrm{X}_2 \mathrm{O_4(l}) \longrightarrow 2 \mathrm{XO}_2(\mathrm{g}), \Delta U=2.1 \mathrm{~kcal}, \Delta S=20 \mathrm{~cal} \mathrm{~K}^{-1}

300 \mathrm{~K}

. Hence,

\Delta G