PUC Science 2nd PUC Class 12 - Karnataka Board PUC Important Questions for Chemistry

Which stoichiometric defect does not change the density of the crystal?

Write the type of magnetism observed when the magnetic moments are aligned in parallel and anti-parallel directions in unequal numbers.

Which stoichiometric defect decreases the density of the crystal?

Explain ionic solids are hard and brittle.

Define Molarity (M).

In the complexes `[Fe(CN)_6]^(3-)` and `[pt(en) (H_2O)_2(NO_2 (Cl)^(2+)]``the respective oxidation numbers of central metal atoms are

1) +3 and +4

2) +6 and + 4

3) +6 and +3

4) +3 and + 3

Define “Molar conductivity”.

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.

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.

In a first order reaction x → y, 40% of the given sample of compound remains unreacted in 45 minutes. Calculate rate constant of the reaction.

Sucrose decomposes in acid solution to give glucose and fructose according to the first order rate law. The half life of the reaction is 3 hours. Calculate fraction of sucrose which will remain after 8 hours.