What is the term used to define the temperature at which the solid and liquid phases of a pure substance can exist in equilibrium at a particular temperature and atmospheric pressure?

(a) Normal melting point

(b) Equilibrium temperature

(c) Boiling point

(d) Freezing point

Choose the correct option:

1.	(a, b)	2.	(b, c)
3.	(c, d)	4.	(a, d)

For the reaction N₂O₄(g) ⇌ 2NO₂(g), the value of K(equilibrium constant) is 50 at 400 K and 1700 at 500 K. Which of the following option(s) is/are correct?

1. (a, b, d)

2. (b, c, d)

3. (b, d, a)

4. (a, c, d)

Which of the following acids forms three series of salts?

The correct decreasing order of basic strength of the following species is.

${\mathrm{H}}_2\mathrm{O},{\mathrm{NH}}_3,{\mathrm{OH}}^{-},{\mathrm{NH}}_2^{}$

$1.<mspace\; width="1em"></mspace>{\mathrm{NH}}_2^{-}>{\mathrm{OH}}^{-}>{\mathrm{NH}}_3>{\mathrm{H}}_2\mathrm{O}$
$2.<mspace\; width="1em"></mspace>{\mathrm{OH}}^{-}>{\mathrm{NH}}_2^{-}>{\mathrm{H}}_2\mathrm{O}>{\mathrm{NH}}_3$
$3.<mspace\; width="1em"></mspace>{\mathrm{NH}}_3>{\mathrm{H}}_2\mathrm{O}>{\mathrm{NH}}_2^{-}>{\mathrm{OH}}^{-}$
$4.<mspace\; width="1em"></mspace>{\mathrm{H}}_2\mathrm{O}>{\mathrm{NH}}_3>{\mathrm{OH}}^{-}>{\mathrm{NH}}_2^{-}$

At 500 K, equilibrium constant, K_c, for the following reaction is 5.

$\frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{I}}_2\left(\mathrm{g}\right)\rightleftharpoons \mathrm{HI}\left(\mathrm{g}\right)$

What would be the equilibrium constant K_c for the reaction?

$2\mathrm{HI}\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{I}}_2\left(\mathrm{g}\right)$

1.  0.04

2.  0.4

3.  25

4.  2.5

On increasing the pressure, the direction in which the gas phase reaction proceeds to re-establish equilibrium is predicted by applying Le-Chatelier's principle. Consider the reaction,

${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$

Which of the following is correct, if the total pressure at which the equilibrium is established is increased without changing the temperature?

Which of the following alternatives best describes the reaction A ⇌ B at its halfway point?
1. \(\Delta G^{\ominus}=0\)
2. \(\Delta G^{\ominus}>0\)
3. \(\Delta G^{\ominus}<0\)
4. \(\Delta G^{\ominus}=-RTlnK\)

${\mathrm{K}}_{\mathrm{a}}$ for ${\mathrm{CH}}_3\mathrm{COOH}$ is $1.8\times {10}^{-5}$ and K_b for ${\mathrm{NH}}_4\mathrm{OH}$ is $1.8\times {10}^{-5}$. The pH of ammonium acetate will be: 

1. 7.005

2. 4.75

3. 7.0

4. Between 6 and 7

The value of the pH of \(0.01 \) \(\text{mol dm}^{-3}   \)\(\text{CH}_3\text{COOH}\) \(\left(K_a=1.74 \times 10^{-5}\right)\)  is: