What is the covalent compound formula for ${{N}_{2}}{{O}_{5}}$?

Hint: Covalent compounds are the compounds that consist of covalent bonds. A covalent bond is formed by the sharing of valence electrons between the atoms. A covalent compound consists of atoms with relatively the same electronegativity. This given compound has 2 nitrogen atoms and 5 oxygen whose formula is determined.

Complete answer:
Covalent compounds are formed by sharing an electron pair to form covalent bonds. A chemical formula for any covalent compound represents the total number of atoms involved in a molecule. While writing the covalent compound formula, IUPAC has suggested some rules like the non – metal with a lower group number and at the bottom is written first and then the non – metal which has a higher group number and top position in a group. Also the name of the non – metal that is written at the end has a prefix and suffix added. The prefix denotes the number of the preceding atom, like di, tri, etc. and the suffix is the conversion of the end to ‘ide’.
We have 2 nitrogen and 5 oxygen atoms. We know that oxygen comes after nitrogen in the periodic table, so nitrogen will be written first and then oxygen. As nitrogen atoms are 2 in number, so ‘di’ is used for them. While, oxygen is written at the end so, it is changed to oxide with a prefix ‘penta’ to denote 5 nitrogen atoms.
So, the covalent compound formula becomes dinitrogen pentoxide as ${{N}_{2}}{{O}_{5}}$.
Hence, the covalent compound formula of N₂O₅ is ${{N}_{2}}{{O}_{5}}$ dinitrogen pentoxide.

Note:
The rules for writing formula and names of covalent and ionic compounds have a slight difference. In ionic compounds the cations are named and written first and then the anions, while in covalent compounds the less electronegative element is written first and then the more electronegative element is written.