Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

Download the PDF Sample Papers Free for off line practice and view the Solutions online.

ISC Class 12 Chemistry Solved Question Paper 2018

Short Answer Type

41.

Name the sulphide ore of Copper. Describe how pure copper is extracted from this ore.

42.

Calculate the emf and △G^o for the cell reaction at 25^oC:

Zn(s)|Zn²⁺(aq) ||Cd²⁺ (aq)| Cd(s)

Zn²⁺(aq) = (0.1 M)

Cd²⁺ (aq) = (0.01 m)

Given E^o Zn²⁺/Zn = -0.763 and E^o Cd²⁺/Cd = -0.403 V

43.
Define the following terms :
(1) Equivalent conductivity
(2) Corrosion of metals

(1) It is defined as conductivity power of all ions produced by dissolving one gram equivalent of an electrolyte in solution,

$\land_{e} = \frac{k x 1000}{C}$

(2) When the surface of a metal is attacked by air, water and some other substance, it is said to corrode. The phenomenon is known as corrosion.

When iron is exposed to moist air for a long time, its surface acquires a coating of a brown, flaky substance. The brown surface easily peel off the iron surface, which if exposed further to moist air again acquires more of that brown layer. This is due to corrosion of iron in moist-air. The flaky substance formed is called rusk Rust is mainly hydrated ferric oxide, Fe₂O₃ · xH₂O.

Another example is copper metal. The surface of copper in moist air acquires a green coating of basic copper carbonate, Cu(OH)₂ or CuCO₃.

44.

The specific conductivity of a solution containing 5 g of anhydrous BaCl₂ (mol. wt = 208) in 1000 cm³ of a solution is found to be 0.0058 ohm^–1cm^–1. Calculate the molar and equivalent conductivity of the solution.