Chlorine has 17 electrons
Lets look at Electronic configuration
[tex]\\ \bull\sf\dashrightarrow 1s^22s^22p^63s^23p^5[/tex]
- It require 1 electron to become Argon.
Required configuration should be
[tex]\\ \bull\sf\dashrightarrow 1s^22s^22p^63s^23p^6[/tex]
Now
Symbol will be
[tex]\\ \bullet\sf\dashrightarrow {}_{35}Cl^{1-}[/tex]
Option A is correct
