Answer:

Explanation:
Hello!
In this case, since the percent water is computed by dividing the amount of water by the total mass of the hydrate; we infer we first need the molar mass of water and that of the hydrate as shown below:

Thus, the percent water is:

So we plug in to obtain:

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Answer:
The answer I believe is B. Erosion
Explanation:
Just sounds better than all the other choices.
Answer:
I hope this link helps you.
Explanation:
http://astronomy.swin.edu.au/cosmos/P/Phases
Answer:

Explanation:
Hello!
In this case, according to the chemical reaction:

We can evidence the 2:1 mole ratio between hydrogen and tin, thus, we perform the following stoichiometric setup to obtain the mass of produced tin:

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The amount of HCl required for one experiment - 13.5 µl
the volume in terms of L - 13.5 x 10⁻⁶ L
the volume of HCl available - 0.250 L
since one experiment uses up - 13.5 x 10⁻⁶ L
then number of experiments - 0.250 L / 13.5 x 10⁻⁶ L = 1.8 x 10⁴ times
the experiment can be carried out 18000 times