Answer: Protons
WHY?
Changing electrons will only result in the same element having different charges and hence, changing it's chemical properties.
Changing neutrons will not change an element but it will result in an isotope forming instead. (Isotopes are elements of the same type with different neutron numbers.)
However, changing the proton number would immediately change the nucleus composition, resulting in a change in element with a negative charge as there are more electrons than protons. This results in a expansion in valance electrons's distance from the nucleus. This results in a change in chemical properties of the element.
Therefore, a change in Protons is the answer.
<u>Answer:</u> Copper is getting oxidized and is a reducing agent. Silver is getting reduced and is oxidizing agent.
<u>Explanation:</u>
Oxidation reaction is defined as the reaction in which an atom looses its electrons. Here, oxidation state of the atom increases.

Reduction reaction is defined as the reaction in which an atom gains electrons. Here, the oxidation state of the atom decreases.

Oxidizing agents are defined as the agents which oxidize other substance and itself gets reduced. These agents undergoes reduction reactions.
Reducing agents are defined as the agents which reduces the other substance and itself gets oxidized. These agents undergoes reduction reactions.
For the given chemical reaction:

The half reactions for the above reaction are:
<u>Oxidation half reaction:</u> 
<u>Reduction half reaction:</u> 
From the above reactions, copper is loosing its electrons. Thus, it is getting oxidized and is considered as a reducing agent.
Silver is gaining electrons and thus is getting reduced and is considered as an oxidizing agent.
Answer:
Covalent bonding
Explanation:
Sulfur Dioxide is a process of covalent bonding, since Sulfur and Oxygen are both non-metals. The Sulfur is in the center surrounded by 2 Oxygen atoms.