The enthalpies of elements in their standard states are taken as zero. The enthalpy of formation of a compound is-

1.	Generally negative	2.	Always positive
3.	Zero	4.	Never negative

The enthalpy of sublimation of a substance is equal to:

1. Enthalpy of fusion + Enthalpy of vaporization
2. Enthalpy of fusion
3. Enthalpy of vaporization
4. Twice the enthalpy of vaporization

Which of the following is not correct?

1. $∆\mathrm{G}$ is zero for a reversible reaction.

2. $∆\mathrm{G}$ is positive for a spontaneous reaction.

3. $∆\mathrm{G}$ is negative for a spontaneous reaction.

4. $∆\mathrm{G}$ is positive for a non-spontaneous reaction.

Based on the reactions, ascertain the valid algebraic relationship:
$\left(i\right)$ $C\left(g\right)$ $+4H$ $\left(g\right)$ $\to C{H}_4\left(g\right);$ $$
$∆H_r$ $=x$ $kJ$ $mo{l}^{-1}$
$\left(ii\right)$ $C\left(graphite\right)$ $+$ $2H_2$ $\left(g\right)$ $\to$ $$ $C{H}_4;$ $$
$∆H_r$ $$ $=$ $y$ $kJ$ $mo{l}^{-1}$

Which of the following algebraic relationships is correct based on the given thermochemical equations?

1. z=x+y

2. x=y-z

3. x=y+z

4. y=2z-x

The entropy change can be calculated by using the expression $∆\mathrm{S}=\frac{{\mathrm{q}}_{\mathrm{rev}}}{\mathrm{T}}$. When water freezes in a glass beaker, the correct statement among the following is:

The pressure-volume work for an ideal gas can be calculated by using the expression $\mathrm{W}={\int }_{{\mathrm{V}}_{\mathrm{i}}}^{{\mathrm{V}}_{\mathrm{f}}}{\mathrm{p}}_{\mathrm{ext}}d\mathrm{V}$.

The work can also be calculated from the pV-plot by using the area under the curve within the specified limits.
An ideal gas is compressed (a) reversibly or (b) irreversibly from volume ${\mathrm{V}}_{\mathrm{i}}$ to ${\mathrm{V}}_{\mathrm{f}}$.
The correct option is:

1. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)=\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{irreversible}\right)$

2. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)<\mathrm{W}\hspace{0.17em}\left(\mathrm{irreversible}\right)$

3. $\mathrm{W}<mspace\; width="1em"></mspace>(\mathrm{reversible})\; >\mathrm{W}<mspace\; width="1em"></mspace>(\mathrm{irreversible})$

4. $\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{reversible}\right)=\mathrm{W}<mspace\; width="1em"></mspace>\left(\mathrm{irreversible}\right)+{\mathrm{p}}_{\mathrm{ext}}.∆\mathrm{V}$

In an adiabatic process, no transfer of heat takes place between the system and its surroundings. The correct option for free expansion of an ideal gas under adiabatic condition from the following is:

1. $\mathrm{q}=0,<mspace\; width="1em"></mspace>∆\mathrm{T}\ne 0,<mspace\; width="1em"></mspace>\mathrm{W}=0$

2. $\mathrm{q}\ne 0,<mspace\; width="1em"></mspace>∆\mathrm{T}=0,<mspace\; width="1em"></mspace>\mathrm{W}=0$

3. $\mathrm{q}=0,<mspace\; width="1em"></mspace>∆\mathrm{T}=0,<mspace\; width="1em"></mspace>\mathrm{W}=0$

4. $\mathrm{q}=0,<mspace\; width="1em"></mspace>∆\mathrm{T}=0,<mspace\; width="1em"></mspace>\mathrm{W}\ne 0$

${The\; standard\; internal\; energy\; change\; of\; formation,\; \Delta fU°,\; of\; CH₄(g)\; at\; a\; certain\; temperature\; is\; –393\; kJ\; mol⁻¹.}_{}$

Find the value of the standard enthalpy of formation (ΔfH°).
1. Zero

2. Less than ΔfU°

3. Greater than ΔfU°

4. Equal to ΔfU°

During the complete combustion of one mole of butane, 2658 kJ of heat is released. The thermochemical reaction for this change is: