<u>Answer:</u> The correct net ionic equation for the reaction is 
<u>Explanation:</u>
Net ionic equation is defined as the equations in which spectator ions are not included.
Spectator ions are the ones that are present equally on the reactant and product sides. They do not participate in the reaction.
The balanced molecular equation is:

The complete ionic equation follows:

As calcium and sulfate ions are present on both sides of the reaction. Thus, they are considered spectator ions.
The net ionic equation follows:

Hence, the correct net ionic equation for the reaction is 
Answer:
B
B
A
C
Explanation:
3
B. Vanillin as a phenoxide ion (conjugate base)
4
B. Protonation of acetic anhydride
5
A. 1.97 mmol of vanillin and 8.45 mmol acetic anhydride
6
C. 1 mmol of vanillin and 10.6 mmol acetic anhydride
This is probably true but I’m not 100% sure
The distance of the earth to the sun in Mm = 1.5 x 10⁵
<h3>Further explanation</h3>
Given
The distance of the earth to the sun : 1.50 x 10⁸ km
Required
The distance in Mm
Solution
In converting units we must pay attention to the conversion factor.
the conversion factor :
1 kilometer(km) = 10⁻³ megameter(Mm)
So the distance conversion :
1.5 x 10⁸ x 10⁻³ = 1.5 x 10⁵ Mm