You catch, tag, and release 35 fish back into a pond. Then, you catch 70 more fish, 12 of which have tags on them, What is the best estimate of the number of fish in the pond?
a 100
b 150
c 142
d 204

100

Explanation:

70 + 35 is 105 and if the 12 fish were new it would be 117 which is almost 25 away from 142 but 17 away from 100. hope that makes since!  

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.