Answer:
24.5%
Explanation:
You just add up the atomic masses.
Ca - 40.078
Cl2 - 35.4527 x 2 = 70.9054
------ 110.9834
H4 - 1.00794 x 4 = 4.03176
O2 - 31.9998
------ 36.03056
TOTAL - 147.01396
So the water is 36.03056/147.01396 = .245082576 but that is only accurate to three decimals (because the mass of Ca was only given to three decimals) so we write .245 and that is 24.5%
This is not my answer but I found it on Yahoo answers and it was answered by Anonymous.
Answer:

Explanation:
Hello,
In this case, the reaction is given as:

Thus, starting by the yielded grams of silver iodide, we obtain:

Which correspond to the iodide grams in the silver iodide. In such a way, by means of the law of the conservation of mass, it is known that the grams of each atom MUST remain constant before and after the chemical reaction whereas the moles do not, therefore, the mass of iodine from the silver iodide will equal the mass of iodine present in the soluble iodide, thereby:

And the rest, correspond to the iodide's metallic cation which is unknown. Such value has sense since it is lower than the initial mass of the soluble iodide which is 1.454g, so 0.272 grams correspond to the unknown cation.
Best regards.
I think it would be B
hope this works
This one is easy. It's just addition and subtraction. Add the partial pressure of Argon and the partial pressure of Helium:
152 kPa
<u>+305 kPa</u><u>
</u> 457 kPa
Next, subtract the result from the total pressure:
1015 kPa
<u>- 457 kPa</u>
558 kPa
<span>The metal that would more easily lose an electron would be potassium. It is more reactive than sodium. Also, looking on the periodic table, </span><span>from top to bottom for groups 1 and 2, reactivity increases. So, it should be potassium. Hope this answers the question. Have a nice day.</span>