Science (English Medium) Class 12 - CBSE Important Questions for Chemistry

What type of deviation from Roult’s Law is expected when phenol and aniline are mixed with each other? What change in the net volume of the mixture is expected? Graphically represent the deviation.

The vapour pressure of pure water at a certain temperature is 23.80 mm Hg. If 1 mole of a non-volatile non-electrolytic solute is dissolved in 100g water, Calculate the resultant vapour pressure of the solution.

A 5% solution of \[\ce{Na2SO4.10H2O}\] (MW = 3 22) is isotonic with 2% solution of non- electrolytic, non volatile substance X. Find out the molecular weight of X.

Write the two applications of Henry’s law.

Define “Molar conductivity”.

How much electricity in terms of Faraday is required to produce 20 g of Ca from molten CaCl₂?

(Given: Molar mass of Calcium is 40 g mol⁻¹.)

The conductivity of 0.20 M solution of KCl at 298 K is 0.025 S cm⁻¹. Calculate its molar conductivity.

State Kohlrausch Law.

Calculate E°_cell for the following reaction at 298 K:

2Al_(s) + 3Cu⁺²(0.01M) → 2Al⁺³(0.01M) + 3Cu_(s)

Given: E_cell = 1.98V

Using the E° values of A and B, predict which is better for coating the surface of iron [E°(Fe⁺²/Fe) = -0.44V] to prevent corrosion and why?

Given: E° (A⁺²/A)=-2.37 V: E°(B⁺²/B)= -0.14V

The conductivity of 0.001 mol L-1 solution of CH₃COOH is 3.905× 10-5 S cm-1. Calculate its molar conductivity and degree of dissociation (α) Given λ°(H⁺)= 349.6 S cm² mol-1 and λ°(CH₃COO)= 40.9S cm²mol^-1.

Define electrochemical cell

Following reactions occur at cathode during the electrolysis of aqueous sodium chloride solution:

Na+(aq) + e⁻ ⟶ Na (s) E⁰ =  2.71 V

H+(aq) + e⁻ ⟶ `1/2`  H₂ (g) E⁰ = 0.00 V

On the basis of their standard reduction electrode potential (E⁰) values, which reaction is feasible at the cathode and why?

Why does the cell potential of mercury cell remain constant throughout its life?

Define the following terms: Molar conductivity (⋀_m)

Define the following terms: Secondary batteries

Calculate the standard cell potential of a galvanic cell in which the following reaction takes place:

\[\ce{2Cr_{(s)} + 3Cd{^{2+}_{(aq)}} -> 2Cr{^{3+}_{(aq)}} + 3Cd}\]

Calculate the Δ_rG° and equilibrium constant of the reaction.

Define conductivity for the solution of an electrolyte.

What is the effect of catalyst on activation energy of a reaction?

Write the name of the cell which is generally used in transistors. Write the reactions taking place at the anode and the cathode of this cell.