Two moles of PCl₅ were heated in a closed vessel of 2 L. At equilibrium 40% of PCl₅ is  dissociated into PCl₃ and Cl₂.The,value of equilibrium constant is :

• 0.53

• 0.267

• 2.63

• 5.3

What is the equilibrium expression for the reaction

P₄ (s) + 5O₂ (g) $\rightleftharpoons$ P₄O₁₀ (s) ?

• K_c = $\frac{\left[{\mathrm{P}}_4{\mathrm{O}}_{10}\right]}{\left[{\mathrm{P}}_4\right][{\mathrm{O}}_2{]}^5}$

• K_c = $\frac{\left[{\mathrm{P}}_4{\mathrm{O}}_{10}\right]}{5\left[{\mathrm{P}}_4\right]\left[{\mathrm{O}}_2\right]}$

• K_c = [O₂]⁵

• K_c = $\frac{1}{[{\mathrm{O}}_2{]}^5}$

The pH value of 1/1000 N-KOH solution is :

• 3

• 10^-11

• 2

• 11

The temperature dependence of rate constant (k) of a chemical reaction is written in terms of Arrhenius equation, k = Ae^{-E*/ RT}. Activation energy (E*) of the reaction can be calculated by plating

• log k vs $\frac{1}{\mathrm{T}}$

• log k vs $\frac{1}{\log \mathrm{T}}$

• k vs T

• k vs $\frac{1}{\log \mathrm{T}}$

The heats of combustion of carbon monoxide at constant pressure and at constant volume at 27°C will differ from one another by :

• 27 cal

• 54 cal

• 300 cal

• 600 cal

Microcosmic salt is

• Na₄P₂O₇

• Na(NH₄)HPO₄

• Na(NH₃)HPO₄ 4H₂O

• MgNH₄PO₄

A buffer solution is prepared by mixing 0.1 M ammonia and 1.0 M ammonium chloride. At 298 K, the pK_b of NH₄OH is 5.0. The pH of the buffer is

• 10.0

• 9.0

• 6.0

• 8.0

Which of the following behaves as Lewis acid and not as Bronsted acid ?

• HCl

• H₂SO₄

• HSO${}_3^{-}$

• SO₃

719.

Conjugate acid of HF${}_2^{-}$ is

• H⁺

• HF

• F${}_2^{-}$

• H₂F₂

Water is well known amphoprotic solvent. In which chemical reaction water is behaving as a base?

• H₂SO₄ + H₂O → H₃O⁺ + HSO${}_4^{-}$

• H₂O + H₂O → H₃O⁺ + OH^-

• H₂O + NH${}_2^{-}$ → NH₃ + OH^-

• H₂O + NH₃ → NH${}_4^{+}$ + OH^-