721.

Which of the following is not a equilibrium ?

• Ice $\rightleftharpoons$ Water

• I₂(s) $\rightleftharpoons$ I₂(g)

• S (l) $\rightleftharpoons$ S (g)

• 3O₂ $\rightleftharpoons$2O₃

The standard emf of a cell, involving one electron change is found to be 0.591 V at 25°C. The equilibrium constant of the reaction is (F = 96500 C mol^-1)

• 1.0 × 10¹

• 1.0 × 10⁵

• 1.0 × 10¹⁰

• 1.0 × 10³⁰

Which of the following oxides is amphoteric in character?

• SnO₂

• SiO₂

• CO₂

• CaO

The pH of 10^-8 M NaOH aqueous solution at 25°C, is

• 7.02

• 7.0

• 6.89

• 6.0

Which of the following is not a buffer ?

• NH₃ + HCl

• CH₃COOH + NaOH

• HCOOH + HCOOK

• NaOH + NaNO₃

The buffering action of an acidic buffer is maximum when its pH is equal to

• 5

• 7

• 1

• pK_a

At a certain temperature, the solubility of the salt, M_mA_n in water is s mol/L. The solubility product of the salt is

• M^mAⁿ

• (m + n)s^{m + n}

• m^mnⁿs^{m + n}

• m^mAⁿs

The conjugated base of hydrazoic acid is

• HN${}_3^{-}$

• N${}_2^{-}$

• N${}_3^{-}$

• N^3-

The pK_a value of (I) 2 - bromo propanoic acid, (II) 2-fluoro propanoic acid, (III) 3 - fluoro propanoic acid, (IV) 3- bromo propanoic acid decreases as

• I > III > IV > II

• II > IV > III > I

• I > IV > III > II

• IV > I > III > II

Which is the strongest Lewis base ?

• SbH₃

• AsH₃

• PH₃

• NH₃