Answer: Oxidation number of chlorine in potassium chlorate...
so, oxidation state of chlorine in potassium chlorate is +1. and yea!!
Explanation: hope this help
Number 1: (A.)
Number 2: (A.)
Number 3: (B.)
I'm probably wrong but that is what i think
The answer is (4) Ag(s)
Solid Silver has a Face Centered Cubic crystal structure.
The remaining choices are gases (H2 & Ar) and liquid (Br). Liquids and gases do not form crystal structures as their atoms are loose.
Reaction:

Magnesium is a stronger reducing agent than copper and is thus able to reduce copper(II) oxide.
Products of the reaction: Magnesium oxide and metallic copper.