Question

Why cacl2 and alcl3 is written as chloride and nacl is also chloride?

Answer 1

CaCl2 is Calcium Chloride
AlCl3 is Aluminium Chloride
NaCl is Sodium Chloride
These all have chlorine in common they belong to the chlorine family thus it gets it's name from that chloride

Answer 2

Why cacl2 and alcl3 is written as chloride and nacl is also chloride?

EXPLAINATION :

As these all salts belong to a common family of chlorine (chloride).