Let H be the set of squares of Q. Which statement is true?
H is a subgroup of the additive group of Q.
H is a subgroup of the multiplicative group Q\{0}.
Neither of the above.
No,
12+22 = 5 is not a square in Q.
No,
0 = 02 is a square in Q but does not belong to Q\{0}.
(The nonzero squares do form a subgroup of Q\{0}.)
True.