Answer:
D.
Explanation:
The action of clearing a wide area of trees.
Answer:
The individual substances in a mixture can be separated using different methods, depending on the type of mixture. These methods include filtration, evaporation, distillation and chromatography.
Explanation:
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% .
Grinding as it’s a physical not chemical change :)
Answer:
Number of moles of iron are 4 mol.
Explanation:
Given data:
Mass of iron = 223.4 g
Number of moles = ?
Solution:
Molar mass of iron = 55.85 g/mol
Formula:
Number of moles = mass/molar mass
Number of moles = 223.4 g/ 55.85 g/mol
Number of moles = 4 mol