Option 1: This statement is true. Diamond is made up of carbon atoms, and each carbon atom is indeed linked to four other carbon atoms. This arrangement creates a strong and rigid structure.
Option 2: This statement is true. Diamond has a three-dimensional network structure of carbon atoms. This arrangement gives diamond its hardness and unique properties.
Option 3: This statement is true. Diamond is commonly used as an abrasive material for sharpening and cutting hard tools. Its hardness makes it effective for these purposes.
Option 4: This statement is not true. Diamond cannot be used as a lubricant. In fact, diamond has a low coefficient of friction, which means it has high resistance to sliding. This property makes it unsuitable as a lubricant.
In conclusion, option 4 is the correct answer as it is the only statement that is not true for diamond. Diamond cannot be used as a lubricant.