Answer:
531–1532 – Pizarro's third voyage to Peru. Spaniards form a bond with the Natives (Huancas, Chankas, Cañaris and Chachapoyas) who were under the oppression of the Inca Empire, and Pizarro includes them among his troops to face the Incas. Atahualpa is captured by Spanish.
Explanation: Is this right ?
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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% .
All are true except the statement that ions are formed by changing the number protons in an atom’s nucleus.
A neutral atom contains the same number of protons (positive charge) and electrons (negative charge).
If there are <em>more electrons than protons</em>, the atom becomes a <em>negative ion</em>.
If there are <em>fewer electrons than protons</em>, the atom becomes a <em>positive ion</em>.
The protons are in the nucleus, where we can’t easily get at them. The <em>electrons are outside the nucleus</em>, so other chemicals can easily get at them and either remove them or add to their number.
<em>Metals</em> have only a few valence electrons, so it is fairly easy to remove them and <em>form positive ions</em>.
Answer:
Explanation:
Given parameters :
Volume of solution = 100mL
Absorbance of solution = 0.30
Unknown:
Concentration of CuSO₄ in the solution = ?
Solution:
There is relationship between the absorbance and concentration of a solution. They are directly proportional to one another.
A graph of absorbance against concentration gives a value of 0.15M at an absorbance of 0.30.
The concentration is 0.15M
Also, we can use: Beer-Lambert's law;
A = ε mC l
where εm is the molar extinction coefficient
C is the concentration
l is the path length
Since the εm is not given and assuming path length is 1;
Then we solve for the concentration.
