Would Mg+Ca(NO3)2 yield Mg(NO3)2)+Ca? Thank you for checking.

Under the right conditions, yes. But this problem is similar to those posted earlier. Both Mg and Ca react with water; therefore, this can't be in a water solution. And there is no indication that it is molten. I liked Bob Pursley's answer to one of these when he responded, "This is a textbook problem, not a real one."