Answer: After three half-lives 1/8 (12.5%) of the original sample remains
To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. In this case, the equation becomes 186.207=187*0.626+185*x where x is the percent abundance of 185. The answer is 0.374 or 37.4%. This can also be obtained by 100%-62.6%= 37.4%.
<u>Answer:</u>
211.9 J
<u>Explanation:</u>
The molecules of water release heat during the transition of water vapor to liquid water, but the temperature of the water does not change with it.
The amount of heat released can be represented by the formula:

where
= heat energy,
= mass of water and
= latent heat of evaporation.
The latent heat of evaporation for water is
and the mass of the water is
.
The amount of heat released in this process is:
211.9 J
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