$∆{\mathrm{S}}_{\mathrm{surr}}$ 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.

365.

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

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)

An endothermic reaction with high activation energy for the forward reaction is given by the diagram

For the reaction of one mole of zinc dust with one mole of sulphuric acid in a bomb calorimeter, $∆$U and w corresponds to

• $∆$U < 0, w = 0

• $∆$U < 0, w < 0

• $∆$U > 0, w = 0

• $∆$U > 0, w > 0