Answer: The first isotope has a relative abundance of 79% and last isotope has a relative abundance of 11%
Explanation: Given that the average atomic mass(M) of magnesium
= 24.3050amu
Mass of first isotope (M1) = 23.9850amu
Mass of middle isotope (M2)=24.9858amu
Mass of last isotope(M3)= 25.9826amu
Total abundance = 1
Abundance of middle isotope = 0.10
Let abundance of first and last isotope be x and y respectively.
x+0.10+y =1
x = 0.90-y
M = M1 × % abundance of first isotope + M2 × % of middle isotope +M3 ×% of last isotope
24.03050= 23.985× x + 24.9858 ×0.10 + 25.9826×y
Substitute x= 0.90-y
Then
y = 0.11
Since y=0.11, then
x= 0.90-0.11
x=0.79
Therefore the relative abundance of the first isotope = 11% and the relative abundance of the last isotope = 79%
Answer:
A) Sample B has more calcium carbonate molecules
Explanation:
M = Molar mass of calcium carbonate = 100.0869 g/mol
= Avogadro's number = 
For the 4.12 g sample
Moles of a substance is given by

Number of molecules is given by

For the 19.37 g sample

Number of molecules is given by


So, sample B has more calcium carbonate molecules.
The ratio of the elements of carbon, oxygen, calcium atoms, ions, has to be same in both the samples otherwise the samples cannot be considered as calcium carbonate. Same is applicable for impurities. If there are impurites then the sample cannot be considered as calcium carbonate.
Unlikely. It's unlikely for ammonium ion
to accept a proton
and act as a Bronsted-Lowry Acid.
<h3>Explanation</h3>
What's the definition of Bronsted-Lowry acids and bases?
- Bronsted-Lowry Acid: a species that can donate one or more protons
in a reaction.
- Bronsted-Lowry Base: a species that can accept one or more protons

Ammonium ions
are positive. Protons
are also positive.
Positive charges repel each other, which means that it will be difficult for
to accept any additional protons. As a result, it's unlikely that
will accept <em>any</em> proton and act like a Bronsted-Lowry Base.
I believe it’s B I apologize if it’s wrong
<span>Their outer shells are filled So much that they don't need to bond or react with any other atoms.</span>