Answer:
1) Fe = 69.9%
O = 31.1%
2) H = 5.19%
O = 16.5%
N = 28.9%
C = 49.5%
Explanation:
One easy way to do percent compositions is to assume you have 100g of a substance.
1) Lets say we have 100g of Fe2O3. 
The total molar mass would be:

The molar mass of the Fe2 alone is:

Thus, the grams of Fe2(out of a 100) could be calculated by multiplying 100g * the molar mass ratio of Fe2 to the whole:
 
Which is approximately 69.9%.
We can find the amount of O3 by simply subtracting, as the rest of the compound is made of O3. Thus, the % composition of O3 is 31.1%
You can then do this same process to the next question, getting us the following:
H = 5.19%
O = 16.5%
N = 28.9%
C = 49.5%
 
        
             
        
        
        
The factor in determining the average atomic mass of an element is: 
B or 2 relative abundance of each isotope because the by looking at how many protons , electrons and neutrons the most isotope is of the element has relative abundance. 
        
                    
             
        
        
        
Scoria
Explanation:
Scoria is a  rock that is commonly made up of gas bubbles and minerals such as hornblende, muscovite, olivine, lucite and or plagioclase. 
Scoria is an extrusive igneous rock with a lot of cavities and vesicles indicating gas bubbles. 
- Scoria is product of basaltic magma. 
- It has nearly the same composition as basalt since it originates from it. 
- They silica deficient and very fine grained with holes in them. 
- The holes shows channels by which trapped gases are forcefully ejected out. 
- They are usually found associated with cindercone volcanoes. 
learn more: 
Volcanoes brainly.com/question/5055821
#learnwithBrainly
 
        
             
        
        
        
In an atom, the number of neutrons determines most specifically the isotopes of an element.
<h2>Further Explanation</h2><h3>An atom  </h3>
- An atom is defined as the smallest particle of an element that can take part in a chemical reaction.
- Atoms are made of energy shells and the inner nucleus.
- It is also made up of subatomic particles, protons and neutrons.
<h3>Neutrons  </h3>
- They are sub-atomic particles in an atom that are found in the nucleus of an atom. They have a zero charge or no charge.
- Neutrons are slightly heavier than protons.
- The number of protons and neutrons in a nucleus of an atom results to the atomic mass number of an atom. Like protons they only take part in nuclear reactions.
<h3>Protons</h3>
- Protons are subatomic particles that are found in the nucleus of an atom. They are positively charged. with a charge of +1.
- The number of protons differ from one element to another and thus used as the atomic number of an individual element.
- The nucleus of an atom is positively charged due to the positive charge of the protons.  
- Additionally, protons do not take part in chemical reactions but in nuclear reactions.
<h3>Electrons  </h3>
- They are found orbiting the nucleus on energy shells based on Clouds’ theory. Electrons are negatively charged each with a charge of -1.
- The number of electrons and protons in a neutral atom are equal. Additionally they have the least mass of the three sub-atomic particles.
- Electrons are the only sub-atomic particles that take part in chemical reactions.
<h3>Isotopes </h3>
- Isotopes are atoms of the same element that have the same mass number but different atomic number.
<h3>Mass number;</h3>
- Mass number is the sum of the number of protons and neutrons in the nucleus of an atom of an element.
Keywords: Atom, sub-atomic particles, electrons, protons, neutrons, isotopes  
<h3>Learn more about:</h3>
Level: High school
Subject: Chemistry  
Topic: Atomic structure
 
        
                    
             
        
        
        
Answer:
Angiosperms are vascular plants. ... Unlike gymnosperms such as conifers and cycads, angiosperm's seeds are found in a flower. Angiosperm eggs are fertilized and develop into a seed in an ovary that is usually in a flower. The flowers of angiosperms have male or female reproductive organs.