Plus Two Chemistry Notes & Assignments 

Chapter - 01. SOLID STATE 

1. What are the characteristics properties of solid state    

(i) They have definite mass, volume and shape. 

(ii) Intermolecular distances are short. 

(iii) Intermolecular forces are strong. 

(iv) Their constituent particles (atoms, molecules or ions) have fixed positions and can only oscillate about their mean positions. 

(v) They are incompressible and rigid. 

2. Write any four difference between crystalline and amorphous solid 

 Crystalline solid

 Amorphous solid

Definite

 

characteristic geometrical shape

Irregular shape

Melt at a sharp and

 

characteristic temperature

Gradually soften over a range of temperature

When cut with a

 

sharp edged tool, they split into two pieces and the newly generated surfaces are plain and smooth

When cut with a sharp edged tool, they cut into two pieces with irregular surfaces

They have a definite

 

and characteristic enthalpy of fusion

They do not have definite enthalpy of fusion

Anisotropic in nature

Isotropic in nature



3 . Why are solids rigid?                

At sufficiently low temperature, the thermal energy is low and intermolecular forces bring them so close that they cling to one another and occupy fixed positions. These can still oscillate about their mean positions and the substance exists in solid state.  

(i) They have definite mass, volume and shape. 

(ii) Intermolecular distances are short. 

(iii) Intermolecular forces are strong. 

(iv) Their constituent particles (atoms, molecules or ions) have fixed 

positions and can only oscillate about their mean positions. 

(v) They are incompressible and rigid

4. Explain crystalline solid?          

Crystalline solids can be classified in various ways. The method depends on the purpose in hand. Here, we will classify crystalline solids on the basis of nature of intermolecular forces or bonds that hold the constituent particles together. These are —  

(i) Van der waals forces 

(ii) Ionic bonds  

(iii) Covalent bonds  

(iv) Metallic bonds.  On this basis, crystalline solids are classified into four categories viz., 

molecular, ionic, metallic and covalent solids   

5. Write a note about molecular solids. 

• Molecules are the constituent particles of molecular solids. These are further sub divided into the following categories: 

(i) Non polar Molecular Solids: They comprise either atoms, for example, argon and helium or the molecules formed by non polar covalent bonds, for example, H2, Cl2  and I2. 

(ii) Polar Molecular Solids: The molecules of substances like HCl, SO2,etc. are formed by polar covalent bonds. The molecules in such solids are held together by relatively stronger dipole-dipole interactions. 

(iii) Hydrogen Bonded Molecular Solids: The molecules of such solids contain polar covalent bonds between H and F, O or N atoms. Strong hydrogen bonding binds molecules of such solids like H2O (ice).

6. Why do solids have a definite volume?         

The intermolecular force present in solid are very strong. The constituent particles of solid have fixed positions that is they are rigid. Hence solids have definite volume. 

7. Classify the following as amorphous or crystalline solids:

  Polyurethane, naphthalene, benzoic acid, Teflon, potassium nitrate, cellophane, polyvinylchloride, fibre glass, copper 

• Crystalline solids – Benzoic acid , potassium nitrate, copper. 

• Amorphous solid – polyurethane, Teflon, cellophane, polyvinyl chloride and fibre glass.

8. Refractive index of a solid is observed to have the same value along all directions. Comment on the nature of this solid. Would it show cleavage property?             

Solid has same refractive index in al directions. It is isotropic in nature and anamorphic. So it is not show a clean cleavage when cut, it break into pieces with regular surfaces.  

9. Classify the following solids in different categories based on the nature of intermolecular forces operating in them: 

Potassium sulphate, tin, benzene, urea, ammonia, water, zinc sulphide, graphite, rubidium, argon, silicon carbide. 

1. Potassium sulphate – Ionic  

2.  Tin – metallic  

3. Benzene – molecular 

4. Urea -  molecular  

5. Ammonia – molecular (hydrogen bonded) 

6. Water- molecular (hydrogen bonded) 

7. zinc sulphide – ionic  

8. graphite – covalent  

9. rubidium – metallic  

10.  argon – molecular  

11.  silicon carbide–covalent(network) 

Plus Two Chemistry Notes Part -02 Click Here