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

Complete the following reactions:

What happens when \[\ce{CH3 - Br}\] is treated with KCN?

Write the dispersed phase and dispersion medium of the following colloidal systems: 

(i) Smoke

(ii) Milk

Which solution is used for the leaching of silver metal in the presence of air in the metallurgy of silver?

Chlorobenzene is extremely less reactive towards a nucleophilic substitution reaction. Give two reasons for the same.

Account for the following: Oxygen shows catenation behavior less than sulphur.

Write the final product(s) in each of the following reactions:

Give reasons: SO₂ is reducing while TeO₂ is an oxidising agent.

For the complex [Fe(H₂O)₆]+3, write the hybridisation, magnetic character and spin of the complex. (At, number : Fe = 26)

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

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?

Reduction of metal oxide to metal becomes easier if the metal obtained is in liquid state. Why?

For the complex [Fe(CN)₆]^3–, write the hybridization type, magnetic character and spin nature of the complex. (At. number : Fe = 26).

Write the hybridization and magnetic behaviour of the complex [Ni(CO)₄].

(At.no. of Ni = 28)

It is necessary to remove CO when ammonia is prepared by Haber's process.

The presence of nitro group (−NO₂) at o/p positions increases the reactivity of haloarenes towards nucleophilic substitution reactions.

Account for the following : There is large difference between the melting and boiling points of oxygen and sulphur.

Give a simple chemical test to distinguish between the following pair of compounds :

(CH₃)₂NH and (CH₃)₃N

Write the dispersed phase and dispersion medium of butter.

Give reasons for the following : H₂Te is the strongest reducing agent amongst all the hydrides of Group 16 elements.