Answer:- The natural abundance of
is 0.478 or 47.8% and
is 0.522 or 52.2% .
Solution:- Average atomic mass of an element is calculated from the atomic masses of it's isotopes and their abundances using the formula:
Average atomic mass = mass of first isotope(abundance) + mass of second isotope(abundance)
We have been given with atomic masses for
and
as 150.919860 and 152.921243 amu, respectively. Average atomic mass of Eu is 151.964 amu.
Sum of natural abundances of isotopes of an element is always 1. If we assume the abundance of
as n then the abundance of
would be 1-n .
Let's plug in the values in the formula:

151.964=150.919860n+152.921243-152.921243n
on keeping similar terms on same side:


negative sign is on both sides so it is canceled:



The abundance of
is 0.478 which is 47.8%.
The abundance of
is = 
= 0.522 which is 52.2%
Hence, the natural abundance of
is 0.478 or 47.8% and
is 0.522 or 52.2% .
A substance that consist of two elements is one IN WHICH THE ELEMENTS ARE CHEMICALLY COMBINED IN A FIXED PROPORTION.
A compound is a substance that is made up of two or more elements which have undergone chemical reaction together and their individual properties have been lost during the reaction, thus a compound has properties that are different from those of its constituents elements. Compounds are usually combined in specific fixed ratio.<span />
Answer:
B. The amounts of water and alcohol are not the same
Explanation:
Answer:
Moving them farther apart
Explanation:
One can try to change the distance between the two positive charges in such a way that it increases the distance and decreased the electric force.