Groups of atoms that are added to carbon backbones and give them unique properties are known as

             Groups of atoms that are added to carbon backbones and give them unique properties are known as Functional Groups.

Explanation:

                   In organic chemistry they are called as Functional Group because they are the active part of a molecule. These groups give a unique characteristic to molecule both chemically and physically. Also, each functional group represent a different class of compounds.

Examples:

S No.                          Functional Group                                 Name

1                                   R--X                                             Alkyl Halides

2                                   R--OH                                          Alcohols

3                                  R--NH₂                                         Amines

4                                  R--O--R                                         Ethers

5                                   R--CO--R                                      Ketones

6                                   R--CO--H                                     Aldehydes

7                                  R--CO--OH                                  Carboxylic acids

8                                   R--CO--X                                     Acid Halides

10                                R--CO--NR₂                                 Acid Amides

11                                 R--CO-OR'                                  Esters

i think the answer is terrae but not 100 percent sure. ▓▬▬ §

the answer would be a