Arsenic, I believe. Metalloids fall in between metals and nonmetals (usually on the bold line separating the two on the periodic table). And since the metalloid in question has four electron shells and five valence electrons in the outermost shell, you can see that this element is arsenic
Answer: He could add a base to the pool to neutralize the acid.
Explanation:
Chlorine is used to disinfect the pools as it produces hypochlorous acid in water. This hypochlorous acid is unstable and gives hydrochloric acid and nascent oxygen which is used to disinfect.

The excess acid is neutralized by adding base which produces salt and water and thus decrease the acidity.

Adding more acid would increase the acidity further.
(JSYK: this is all considering that only whole batches are included and fractional batches aren't)
Answer: 3 batches (72 cookies), her limiting reactant should be sugar since she only has enough to make three batches exactly, and she will also have 3/4 a cup of flour left over, 2 cups butter, and 5 eggs, in addition to the excess of baking soda and baking powder.
Hope this helps, if not, comment below please!!!
The correct answer is option C