Answer: 12.18 u
Explanation: The average atomic mass of an element is calculated by taking the weighted average of the atomic masses of its stable isotopes.
In other words, each stable isotope will contribute to the average mass of the element proportionally to its abundance.
In keeping with the general trends, K-Br will have the smallest bond energy. The bond energy refers to the energy that keeps the atoms in a bond together.
<h3>What is bond energy?</h3>
Bond energy is the energy that is required to hold atoms together in a bond. This energy must also be supplied when the atoms are to be separated.
We have the bond energies of each of the bons in the question, we have to note that the the smallest value of bond energy is Na-Br hence in keeping with the general trends, K-Br will have the smallest bond energy.
Learn more about bond energies: brainly.com/question/14842720?
Answer : 0.8663 Kg of chalcopyrite must be mined to obtained 300 g of pure Cu.
Solution : Given,
Mass of Cu = 300 g
Molar mass of Cu = 63.546 g/mole
Molar mass of 
= 183.511 g/mole
- First we have to calculate the moles of Cu.
The moles of Cu = 4.7209 moles
From the given chemical formula, we conclude that the each mole of compound contain one mole of Cu.
So, The moles of Cu = Moles of = 4.4209 moles
- Now we have to calculate the mass of .
Mass of = Moles of × Molar mass of = 4.4209 moles × 183.511 g/mole = 866.337 g
Mass of = 866.337 g = 0.8663 Kg (1 Kg = 1000 g)
Therefore, 0.8663 Kg of chalcopyrite must be mined to obtained 300 g of pure Cu.
I believe you just look at your periodic table for this value. I don't think there is any math involved.
Therefore one mole of Mg = 24.305g.
