$∆$H_fusion of a substance is 'x' and $∆$H_vap is 'y', then $∆$H_sublimation will be

• x + y

• x - y

• x/y

• y/x

Assertion : Many endothermic reactions that are not spontaneous at room temperature become spontaneous at high temperature.

Reason : Entropy of the system increases with increase in temperature.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

$∆{\mathrm{S}}_{\mathrm{surr}}$ for an exothermic reaction is

• always positive

• always negative

• zero

• may be positive or negative

Assertion : As a salt such as NaCl dissolves, the Na⁺ and Cl^- ions leaving the crystal lattice acquire far greater freedom.

Reason : In thermodyanamic terms, the formation of solution occurs with a favourable change in free energy, i.e., $∆$H has a high positive value and T$∆$S a low negative value.

• If both assertion and reason are true and reason is the correct explanation of assertion.

• If both assertion and reason are true but reason is not the correct explanation of assertion.

• If assertion is true but reason is false.

• If both assertion and reason are false.

In exothermic reaction heat is :

• given out

• absorbed

• not involved

• given out or absorbed

For a spontaneous process the correct statement is

• entropy of the system always increases.

• free energy of the system always increases.

• total entropy change is always negative.

• total entropy change is always positive.

Distribution law was given by :

• Henry

• Vant Hoff

• Nernst

• Ostwald

The enthaply change ($∆\mathrm{H}$) for the reaction

       $$\begin{gathered} {\mathrm{N}}_{2\left(\mathrm{g}\right) }+ 3{\mathrm{H}}_{2\left(\mathrm{g}\right)} \to 2{\mathrm{NH}}_{3\left(\mathrm{g}\right) \\ } \end{gathered}$$

is -92.38 kJ at 298K . The internal energy change $∆\mathrm{U}$ at 298K is

• -92.38 kJ

• -87.42 kJ

• -97.34 kJ

• -89.9 kJ

669.

A gas can expand from 100 mL to 250 mL under a constant pressure of 2 atm .The work done by gas is :

• 30.38 joule

• 25 joule

• 5 k joule

• 16 joule

$∆{\mathrm{H}}_{\mathrm{f}}^{°}$ (298 K) of methanol is given by the chemical equation

• CH_{4 (g)} + $\frac{1}{2}$O_{2 (g)} →CH₃OH_(g)

• C (graphite) + $\frac{1}{2}$O_{2 (g)} + 2H₂ → CH₃OH_(l)

• C (diamond) + $\frac{1}{2}$O_2(g) + 2H_2(g) → CH₃OH_(l)

• CO_(g) + 2H₂ → CH₃OH_(l)