PUC Science 2nd PUC Class 12 - Karnataka Board PUC Question Bank Solutions for Chemistry

Account for the following:

Cu⁺ ion is unstable in aqueous solution.

From the given data of E⁰ values, answer the following questions :

(1) Why is `E_(((Cu^(2+))/(Cu)))` value exceptionally positive

(2) Why is `E_(((Mn^(2+))/(Mn)))` value is highly negative as compared to other elements

(3) Which is the stronger reducing agents Cr²⁺ or Fe²⁺ ? Give Reason.

What is the effect of temperature on chemisorption ?

How will you distinguish between the following pair of terms?

Crystal lattice and unit cell

Account for the following:

Zn is not considered as a transition element.

Account for the following:

E° value for the Mn³⁺/Mn²⁺ couple is much more positive than that for Cr³⁺/Cr²⁺.

Out of Mn³⁺ and Cr³⁺, which is more paramagnetic and why ?

(Atomic nos. : Mn = 25, Cr = 24)

Why is adsorption always exothermic?

Why does NO₂ dimerise?

Give the significance of a ‘lattice point’.

Name the parameters that characterize a unit cell.

Which of the following lattices has the highest packing efficiency (i) simple cubic (ii) body-centred cubic and (iii) hexagonal close-packed lattice?

What is meant by the term ‘coordination number’?

How would you determine the standard electrode potential of the system Mg²⁺ | Mg?

Consult the table of standard electrode potentials and suggest three substances that can oxidise ferrous ions under suitable conditions.

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

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

Calculate the Δ_rG° and equilibrium constant of the reaction.

Write any two characteristics of chemisorption.

Why are powdered substances more effective adsorbents than their crystalline forms?

Distinguish between the meaning of the terms adsorption and absorption. Give one example of.

What is the difference between physisorption and chemisorption?