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: Mass of gas is 0.001 pounds.
Explanation:
Density is defined as the mass contained per unit volume.
Given : Mass of gas = ?
Density of gas = 
Volume of gas = 389 ml = 0.389 L (1L=1000ml)
Putting in the values we get:
(1g =0.002 lb)
Thus the mass of gas is 0.001 pounds.
Answer:
The mixture is made up of different atoms and pure substance is made up of same type of atom.
The main difference is that mixture can be separated into its component by physical mean while pure substances can not be separated by physical process
Explanation:
Mixture:
- The properties of the mixture are not same and contains the properties of all those component present in it.
- it is a combination of one or more Pure substances and can be separated by simple physical methods.
- it have varying boiling and melting point
Examples are:
- mixture of salt and sand
- Salt water is mixture of water and NaCl and can be separated by physical mean.
- Alloys: its a mixture of different metal
- Air: mixture of gases
Pure Substance:
Pure substances are those made of same type of atoms all elements and compounds are pure substances.
- it can not be separated by simple physical mean
- it have very constant and consistent melting and boiling point
Examples are:
- Water : contain only water molecule
- All elements: all elements are pure substance made of same atoms
- All compounds: can not be separated by physical mean.
33.6 moles are needed to completely react with 84.0 moles of O2
