Answer:
the open bag allowed the gas from the reaction to escape
There are a lot of separation processes. To name a few, these can be distillation, centrifugation, extraction, membrane or sorption process and many other. To know which is the best technique, you should know the property between two substances that have a stark difference. In this case, it is the polarity. Ethyl alcohol is more polar than ethyl ester and less dense. Thus, these two won't mix. So, take advantage of their density difference by decantation or centrifugation.
I would have to say it would be the closest to a gas A.
Answer: Elements in Group 2
Explanation: The periodic table was arranged by Dmitri Mendeleev specifically around similarites in their chemical behaviors. He found that as atomic number increases, at some point an element starts to react in a manner similar to a previous one. When that happened, he would place the larger element under the smaller one, and eventually noticed a periodicity in the table. Elements in a column (Groups) had similiar chemical properties. We know today that these similarities are due to the electron configuration, and that these configurations repeat themselves. He left gaps in the table when he could find an existing element with properties similar to others in that group. I big leap of faith, but it worked. Elements for those missing boxes were eventually discovered.
The density of ice is less than the density of water.
Fun fact: Water is the only known liquid that has this change it density.
