Answer is B, because CaSO3 only has one S
<u>Answer:</u>
<u>For a:</u> The chemical equation for the dissolution of sodium carbonate is 
<u>For b:</u> The net acid-base reaction is 
<u>Explanation:</u>
Dissolution reaction is defined as the reaction in which a solid compound gets dissolved in water to form aqueous solution.
The chemical equation for the dissolution of sodium carbonate follows:

Ionization reaction is defined as the reaction in which an ionic compound dissociates into its ions when dissolved in aqueous solution.
The chemical equation for the ionization of sodium carbonate follows:

Now, the anion formed which is
reacts with water to form conjugate acid.
The chemical equation for the reaction of anion with water follows:

Hence, the net acid-base reaction of the anion formed and water is written above.
The straight horizontal line shows us that the object is moving at a constant speed
The correct answers are
-formation of a precipitate
-bubble formation
-color change
-temperature change
-odor formation
The only one that isn’t correct is change in state of matter. A change in a state of matter does not mean it’s a chemical change. For example, water boiling so it turns into gas is not a chemical change, and is a physical one. Also, water can freeze and turn into ice, which is also still a physical change. If something changes state of matter, it does not necessarily mean it’s a chemical change.