In which of the following reactions, the concentration of product is higher than the concentration of reactant at equilibrium? (K = equilibrium constant)

• A $\rightleftharpoons$ B; K = 0.001

• M  K = 10

• X $\rightleftharpoons$ Y; K = 0.005

• R $\rightleftharpoons$ P; K = 0.01

Study the following table:

Buffer solution	Volume (in mL) of 0 M weak acid	Volume (in mL) of 0.1 M sodium salt of weak acid
I	4.0	4.0
II	4.0	40.0
III	40.0	4.0
IV	0.1	10.0

Which of the two sets of butter solutions have least pH?

• I and II

• I and III

• II and III

• II and IV

Assertion (A): The pH of a buffer solution containing equal moles of acetic acid and sodium acetate is 4.8 (pK_a of acetic acid is 4.8).

Reason (R): The ionic product of water at 25°C is 10^-14mol².L^-2. The correct answer is

• Both (A) and (R) are true and (R) is the correct explanation of (A)

• Both (A) and (R) are true and (R) is not the correct explanation of (A)

• (A) is true but (R) is not true

• (A) is not true but (R) is true

At 550 K, the K_c for the following reaction is 10⁴ mol^-1L $\mathrm{X}\left(\mathrm{g}\right) + \mathrm{Y} \left(\mathrm{g}\right) \rightleftharpoons \mathrm{Z}\left(\mathrm{g}\right)$. At equilibrium, it was observed that $\left[\mathrm{X}\right] =\frac{1}{2}\left[\mathrm{Y}\right] =\frac{1}{2}\left[\mathrm{Z}\right]$. What is the value of [Z] (in mol L^-1) at equilibrium?

• 2 × 10^-4

• 10^-4

• 2 × 10⁴

• 10⁴

The pH of a solution of H₂O₂ is 6.0. Some chlorine gas is bubbled into this solution. Which of the following is correct?

• The pH of resultant solution becomes 8.0

• Hydrogen gas is liberated from resultant solution

• The pH of resultant solunon becomes less than 6.0 and oxygen gas is liberated

• Cl₂O is formed in the resultant solution

Which of the following is not a characteristic property of chemical equilibrium ?

• Rate of forward reaction is equal to rate of backward reaction at equilibrium.

• After reaching the chemical equilibrium, the concentrations of reactants and products remain unchanged with time.

• For A (g) $\rightleftharpoons$ B (g), K_c is 10^-2. If this reaction is carried out in the presence of catalyst, the value of K_c decreases.

• After reaching the equilibrium, both forward and backward reactions continue to take place.

197.

50 mL of H₂O is added to 50 mL of 1 × 10^-3 M barium hydroxide solution. What is the pH of the resulting solution ?

• 3.0

• 3.3

• 11.0

• 11.7

In a 500 mL flask, the degree of dissociation of PCl₅ at equilibrium is 40% and the initial amount is 5 moles. The value of equilibrium constant in mol L^-1 for the decomposition of PCl₅ is

• 2.33

• 2.66

• 5.32

• 4.66

Boron halides behave as Lewis acids because of their  .......... nature.

• proton donor

• covalent

• electron deficient

• ionising

Which of the following is not a conjugate acid-base pair?

• ${\mathrm{HPO}}_3^{2-}, {\mathrm{PO}}_3^{3-}$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{HPO}}_4^{2-}$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{H}}_3{\mathrm{PO}}_4$

• ${\mathrm{H}}_2{\mathrm{PO}}_4^{-}, {\mathrm{PO}}_3^{3-}$