Answer: The ion formed after the reduction of bromine is 
Explanation:
The electronic configuration of Sodium (Na) = ![[Ne]3s^1](https://tex.z-dn.net/?f=%5BNe%5D3s%5E1)
The electronic configuration of Bromine (Br) = ![[Ar]3d^{10}4s^24p^5](https://tex.z-dn.net/?f=%5BAr%5D3d%5E%7B10%7D4s%5E24p%5E5)
From the above configurations, Sodium ion will loose 1 electron in order to gain stable electronic configuration and that electron is accepted by the Bromine atom because it is 1 electron short of the stable electronic configuration.
(oxidation reaction)
(Reduction reaction)
Bromine atom is reduced to form 
Reduction reactions are the reactions in which the element gain electrons.
Oxidation reactions are the reactions in which the element looses its electrons.
The chemist envision reaction take place when molecules/atoms collide with respect to the correct amount of energy and in the correct position so that the bond can be formed.These means that the reaction take place when two or more molecules collides and a reaction occurs.
The answer is D.
The air inside the bubbles is gas and the solid forms the bubble.
Answer: 3 Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same
Explanation:
Physical change mainly physical properties of a substance while the chemical changes remain unchanged. Once there is a change to the chemistry of the substance, this would be classified as a chemical change.