A. and D. would be the best pick for this sort of experiment, but maybe (unlikely) B. because you could see how they could react in certain situations, how they react to danger but I suggest A.
Hope this helps you ☁︎☀︎☁︎
Answer:
See explanation.
Explanation:
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In this case, according to the given information, it turns out possible for us to firstly recall the electron configuration of hydrogen:

To realize that the principal quantum number is 1, the angular is 0 as well as the magnetic one; therefore we infer that all the given n's are not allowed, just l=0 is allowed as well as ml=0 yet the rest, are not allowed.
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B. The unknown solution had the lower concentration.
Explanation:
Osmosis is a phenomenon in which the molecules of the solvent has a tendency to move through a membrane which is semipermeable from lower concentrated side to the higher concentration side, so that the concentrations on both sides of the membrane must be equal.
So the unknown solution may have lesser concentration than the isotonic solution so that molecules of that solution move from less concentrated side to the more concentrated side, so its level drops.
Answer: 
Explanation:
The unbalanced equation is

Balancing this equation, we get:

The pressure in the flask is 3.4 atm.
<em>pV</em> = <em>nRT
</em>
<em>T</em> = (20 + 273.15) K = 293.15 K
<em>p</em> = (<em>nRT</em>)/<em>V</em> = (1.4 mol × 0.082 06 L·atm·K⁻¹mol⁻¹ × 293.15 K)/10 L = 3.4 atm