Answer:
Data supports significantly because we can use the testing(depending sample) before and after we use the same object to test the hypothesis.
Control variable mi amigo
For a closed system, you need two things:
1) a conservation of mass within the boundaries of the system
2) the ability to freely exchange energy to & from the "closed" system with a surrounding external system
So, the answer is <u><em>never</em></u>, since your defining the "system" as the water within the bathtub, and an open bathtub is exposed to evaporation, which is not conserving mass within the defined "system".
<span>Carbon (C) is most likely to form covalent bonds with Beryllium (Be) or Sodium (Na) because they are both metals and covalent bonds are metals that share their valence electrons with the gases / non-metals to get to the stable octet. Krypton is a gas and Selenium is a metalloid</span>
Chemical Bond
The forces that hold atoms make compounds and molecules
