What is not needed in the chemical formula for a covalent compound

a-display of positive and negative charges
b-specific atoms put together in the compound
c-how many of each atom are combined
d-abbreviation for an atoms included

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.