Answer:
Odd answer choices, but I would put "It shows you that water is a reversible reaction, which contains hydrogen and hydroxide reactions."
Explanation:
The first choice is weird, although water can be written as HOH that doesn't help you understand acids and bases.
The third choice doesn't do that either, and there are more ways for water to be formed than that.
The second choice helps you understand acids and bases, specifically, in water's self-ionization process. It also shows you that it is neutral because it is formed from Hydrogen, which is usually present in acids, and a Hydroxide group, which is usually present in bases.
 
        
             
        
        
        
Atomic Mass is equal to the sum of the number of protons and neutrons.
Thus the atomic mass = 3  +  4
  
                                    =   7
        
             
        
        
        
Answer:
the open bag allowed the gas from the reaction to escape
 
        
             
        
        
        
Taking into account the reaction stoichiometry, 340.0 moles  of methane are produced when 85.1 moles of carbon dioxide gas react with excess hydrogen gas
<h3>Reaction stoichiometry</h3>
In first place, the balanced reaction is:
CO₂ + 4 H₄  → CH₄ + 2 H₂O
By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:
- CO₂: 1 mole
- H₄: 4 moles   
- CH₄: 1 mole
- H₂O: 2 moles
<h3>Moles of CH₄ formed</h3>
The following rule of three can be applied: if by reaction stoichiometry 1 mole of CO₂ form 4 moles of CH₄, 85.1 moles of CO₂ form how many moles of CH₄?

<u><em>moles of CH₄= 340.4 moles</em></u>
Then, 340.0 moles  of methane are produced when 85.1 moles of carbon dioxide gas react with excess hydrogen gas
Learn more about the reaction stoichiometry:
brainly.com/question/24741074
brainly.com/question/24653699
#SPJ1
 
        
             
        
        
        
Answer:
Ok so the answer for 9 is 
x/6=4 
x=24
Explanation:
Solve for x by simplifying both sides of the equation, then isolating the variable.