Sorry, I won't understand your words.
Explanation:
In laboratory, carbon dioxide is not obtained from the air, carbon dioxide is prepared from carbonates by adding acids to the carbonates. In this experiment carbon dioxide is prepared by the reaction of marble with hydrochloric acid.
The swimming pools pH is below 7, meaning it is slightly acidic. If you want to make the pH higher, you must add a base which by definition has a pH higher than 7.
D. Add base
Answer: There are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.
Explanation:
Given:
= 0.0023 M,
= ?
= 15.0 mL,
= 0.012 M
Formula used to calculate volume of strontium hydroxide solution is as follows.

Substitute the values into above formula as follows.

Thus, we can conclude that there are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.
C. The mass number is the amount of Protons and electrons there are combined, so 200 - 80 is 120.