If a+b+c = (a+b)+c, where a,b and c are all integers, which property of addition of integers does it satisfy?

Q.

If (a$\times$b) $\times$ c = a $\times$ (b $\times$c), where a,b and c are all whole numbers,then it follows which property?

Q. Which property does this belong to
$a+(-b)=c$, where a, b and c are integers ?

Q. Which property does this belong to
$a+(-b)=c$, where a, b and c are integers ?

Q. An operation * is defined on the set Z of non-zero integers by $a*b=\frac{a}{b}$ for all a, b ∈ Z. Then the property satisfied is
(a) closure
(b) commutative
(c) associative
(d) none of these

Q.

If a+b = b+a for any two rational numbers a and b, then it satisfies the ___ property of addition for rational numbers.