Chemistry:2011:CBSE:[Delhi]:Set-I

This statement means that some of the physical properties of crystalline solids such as electrical resistance or refractive index show different values when measured along different directions in the same crystals.

The molar conductivity of a solution at a given concentration is related to conductivity of that solution, by the following relation –

where _m is molar conductivity and is the conductivity of the solution.

Electrophoresis is the phenomenon of movement of colloidal particles under the applied electric potential.

XeF₂ is a linear molecule and can be drawn as follows:

The IUPAC name of the given compound is 2, 2-dimethylbromopropane.

The solubility order of the given amines is as follows: 
C₆H₅NH₂ < (C₂H₅)₂NH < C₂H₅NH₂

A polymer that can be decomposed by bacteria (micro-organism) is called a biodegradable polymer.
For example: poly--hydroxybutyrate-co--hydroxyvalerate (PHBV) is biodegradable aliphatic polyester.

The process of corrosion is a redox reaction and it involves simultaneous oxidation and reduction reactions. It can therefore be referred as an electrochemical phenomenon. 
In the process of corrosion, due to the presence of air and moisture, oxidation takes place at a particular spot of an object made of iron. That spot behaves as the anode. The reaction at the anode can be written as follows: 
Anodic reaction: Fe(s) Fe²⁺(aq) + 2e^-

Electrons released at the anodic spot move through the metallic object and go to another spot of the object. There in the presence of H⁺ ions, the electrons reduce molecular oxygen. This spot behaves as the cathode. These H⁺ ions come either from H₂CO₃, which is formed due to the dissolution of carbon dioxide from air into water, or from the dissolution of other acidic oxides from the atmosphere in water.

The reaction taking place at cathode is written as follows:

Cathodic reaction: O₂(g) + 2H⁺(aq) + 2e^- 2H₂O(l)

Thus, the overall reaction is:

Fe(s) + O₂(g) + 2H⁺(aq) Fe²⁺(aq) + 2H₂O(l)

Also, ferrous ions are further oxidised by atmospheric oxygen to ferric ions. These ferric ions combine with moisture present in the surroundings to form hydrated ferric oxide (Fe₂O₃.xH₂O) i.e., rust.