Answer:
( A ) element is composed of one kind of atoms only .
( B ) Properties of metals are - they are generally solids at room temperature , they have high melting and boiling points , they normally have high densities ,
Correct option is - All of the above.
( C ) Graphite is a - ( c ) form of carbon .
Step-by-step explanation:
Element - 
Element is composed of all same type of atoms or element is a substance with all same number of protons . 
Element is the smallest or the simplest substance and cannot be broken down using any chemical reaction . 
Metal - 
Elements are classified into metals and non metals . 
Properties of metals are - 
1. State - Metals are generally solid at room temperature , except Mercury , with liquid state at room temperature . 
2. Boiling point and melting point - Metals have a very high boiling and melting point , with Tungsten having the highest melting point . 
3. Density - Metals have high density and are quite heavy , Iridium and osmium have the highest densities . 
Graphite - 
Graphite is one of the allotropic form of carbon .