Is null and 0 are equal

Answer 1

It depends upon the language. In complex languages like C++ and maybe JS, its a no. In SQL, PHP and CSS its usually yes.
In general terms they are the same.
Void also means zero, null or nothing. ("Not in programming")

Answer 2

@Vrishal Prajapati that is true in all cases

Answer 3

No,
null means the the variable has no value.
whereas 0 means that variable has value.

Answer 4

Even in SQL null is not 0 as null+1=null and 0+1=1.