Answer:

Explanation:
Oxygen has eight eletrons and six valence electrons, giving it the electron configuration of
.
2NaBr + Ca(OH)2 ➡️ CaBr2 + 2NaOH
1 mol of formic acid is correct. There are two oxygen atoms in formic acid, compared to just one for the other molecules.
Based on the balanced chemical reaction presented above, every mole of magnesium (Mg) yields one mole of diatomic hydrogen (H2). When converted to masses, every 24.3 grams of magnesium yields 2 grams of hydrogen.
From the given, there are 20 grams of magnesium available for the reaction. With this amount, the expected yield of hydrogen is 1.646 grams. To calculate the percent yield, divide the actual yield to the hypothetical yield.
*The case is impossible because the actual yield is greater than the theoretical yield.
If we assume that there had been a typographical error and that the actual yield is 0.7 grams instead of 1.7 grams, the percent yield becomes 42.5%. Thus, the answer is letter E.
Answer:
See explanation below
Explanation:
You are missing the structure, therefore, I will do an example with one that I found on another place to try to explain.
This acid mechanism always involves carbocations, and positive charges, never negative because we are in acidic mediums.
In the first step, the lone pairs of the oxigen from the epoxide, substract one hydrogen of the reactant.
Second step, the lone pairs of the oxygen from the reactant, do a nucleophylic attack to the carbon of the epoxide. In this case, it will do it to the most substitued carbon.
Then, in the third step by acid base equilibrium, the hydrogen from the reactant that attacked, is substracted from the molecule by a molecule of water (We are in acid medium, therefore, there is traces of water) and the final structure is formed.
Check picture for mechanism: