Question of Exercise 1

Surface Chemistry of Class 12

The coagulation of 100 ml of colloidal solution of gold is completely prevented by addition of 0.25 g of a substance "X" to it before addition of 10 ml of 10% NaCl solution. The gold number of "X" is


Option 1 0.25

Option 2 25

Option 3 250

Option 4 2.5

Frequently Asked Questions

Write the molecular formula of ethanol



The formula for ethyl alcohol or ethanol is C2H5OH or CH3CH2OH


Final Answer:

The formula for ethyl alcohol or ethanol is C2H5OH or CH3CH2OH


The catalyst used in contact process is

A: Al2O3

B: Cr2O3

C: V2O5

D: MnO2




  • Contact process
  • By contact process, H2SO4(Sulphuric acid) is prepared in presence of V2O5(Vanadium oxide).                                           

 SO2 (g)+1/2O2 (g) SO3 (g)

 (Sulphur dioxide) (Oxygen) (Sulphur trioxide)                                                                                                                 

  • The catalyst in the above reaction is V2O5.

Final Answer:

Hence, Option (C) is correct.


What is collodion



Collodion is a flammable, syrupy 4% solution of Nitro cellulose prepared in a mix of alcohol and ether.

Collodion solutions are of two types:

  • Flexible collodion
  • Non-flexible collodion

The two types of collodions find different kinds of utility, e.g: Flexible collodion solutions are used in surgical dressings whereas Non-flexible collodion is used in theatrical make-up, photography, etc.

Collodion solutions also find utility in:

  • Electro- enecephalography
  • Optic cleaning
  • Microscopic study
  • Nail polish, etc.

Final Answer: Collodion solution is a solution of nitrocellulose in ether and alcohol.



Aluminium crystallises in a cubic close packed structure

Its metallic radius is 125 pm.(i) What is the length of the side of the unit cell?(ii) How many unit cells are there in 1.00 cm3 of aluminium?




The length of the side of the unit cell

Final Answer: 

The length of the side of the unit cell =354pm

The number of unit cells in 1.00 cm^3 of aluminium =2.27×1022


Draw the structure of and identify the number

of single P - O bonds .P4O6




It is the anhydride of orthophosphoric acid,  (phosphorus trioxide) therefore also known as phosphorous oxide or phosphorous anhydride. P4O6

It is a solid soft white color. It is an anhydride of an acid so it behaves as  an acidic and will hydrolyze in water to generate phosphorous acid. Phosphorus trioxide is a dimer with the formula . P4O6

Structure of can be shown as: P4O6




Number of single P-O bonds are 12 as shown in the figure.


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