111.

Explain what happens when boric acid is heated.

Explain what happens when boric acid is added to water?

Why is boric acid considered as a weak acid ?

Explain the structure of boric acid. 

Name the elements of group 14 and write down their electronic configuration. 

How do elements of group 14 occur in nature? Give their uses. 

Why does carbon act as abrasive and also as lubricant?

Discuss the characteristics of group 14 elements in terms of:
(i) Atomic radius 
(ii) Ionisation enthalpy
(iii) Electropositive character
(iv) Melting and boiling points.

Explain why is there a phenomenal decrease in ionisation enthalpy from carbon to silicion.

Discuss the characteristics of group 14 elements in terms of:

(i) Oxidation states  
(ii) Metallic character.