I think the answer is white sand (sorry if i am wrong) 
        
                    
             
        
        
        
Answer:
14 moles of oxygen needed to produce 12 moles of H2O.
Explanation:
We are given that balance eqaution

We have to find number of moles of O2 needed  to produce 12 moles of H2O.
From given equation
We can see that
6 moles of   H2O produced by Oxygen =7 moles
 1 mole of   H2O produced by Oxygen= moles
moles
12 moles of H2O produced by Oxygen= moles
moles
12 moles of H2O produced by Oxygen= moles
moles
12 moles of H2O produced by Oxygen=14 moles
Hence, 14 moles of oxygen needed to produce 12 moles of H2O.
 
        
             
        
        
        
When sodium carbonate is dissolved in water, the equation is  .
.
When carbon dioxide is placed in water, aqueous carbon dioxide is formed:  
<h3>Dissolution of compounds in water</h3>
Some compounds are water-soluble, some are just partially soluble, while others are insoluble in water. Some soluble or partially soluble substances dissociate in water into their component ions. These substances are said to be ionic. 
Sodium carbonate, like every other sodium salt, is soluble in water. It dissolves in water to form an aqueous solution of sodium carbonate.
While in solution, sodium carbonate dissociates into its component ions according to the following equation:

Carbon dioxide, on the other hand, does not dissociate in water. Instead, it dissolves in water where most of it remains as aqueous carbon dioxide in equilibrium with a small amount of hydronium ion and hydrogen carbonate ion.
Since the hydronium and hydrogen carbonate ions formed are so minute, the equation of the reaction can be written as: 
More on the dissolution of substances can be found here: brainly.com/question/28580758
#SPJ1
 
        
             
        
        
        
I would say the energy has to be decreased by 87 kj because the bonding is held together by 87 kj so removing that should prevent the bonding from taking place or reverse it I believe. In other words, a certain amount of energy is required to hold the bond together and in the absence of that energy, the bonding will not take place.