(i) Which rational number is its own additive inverse?
(ii) Is the difference of two rational numbers a rational number?
(iii) Is addition commutative on rational numbers?
(iv) Is addition associative on rational numbers?
(v) Is subtraction commutative on rational numbers?
(vi) Is subtraction associative on rational numbers?
(vii) What is the negative of a negative rational number?
(i) A Additive inverse of a number 
is the number 
such that, 
0 is the rational number that is its own additive inverse
(ii) Let there be 2 rational numbers, 
and 
where, b≠0 and d≠0
LCM of b and d = bd
Where, bd ≠ 0
Therefore, 
is a rational number
Hence,
Yes, the difference of two rational numbers a rational number
(iii) Yes, addition is commutative on rational numbers
Let there be 2 rational numbers, 
and 
where, b≠0 and d≠0
Then,
(iv) Yes, addition is associative on rational numbers
Let there be 3 rational numbers, 
, 
and 
where, b≠0 , d≠0 and f≠0
Then,
(v) No, subtraction is not commutative on rational numbers
Let there be 2 rational numbers, 
and 
where, b≠0 and d≠0
Then,
(vi) No, addition is not associative on rational numbers
Let there be 3 rational numbers, 
, 
and 
where, b≠0 , d≠0 and f≠0
Then,
(vii) Negative of a negative rational number is the number itself without the negative sign.