Answer:
D thermosphere
Explanation:
The thermosphere is home to the International Space Station as it orbits Earth. This is also where you'll find low Earth orbit satellites
 
        
             
        
        
        
<u>Answer:</u> The products of the given chemical equation are 
<u>Explanation:</u>
Protonation equation is defined as the equation in which protons get added in the substance.
The chemical equation for the protonation of carbonate ion in the presence of water follows:

By Stoichiometry of the reaction:
1 mole of carbonate ion reacts with 1 mole of water to produce 1 mole of hydrogen carbonate ion and 1 mole of hydroxide ion
Hence, the products of the given chemical equation are 
 
        
             
        
        
        
The  standard  state formation reaction  is  a  chemical  reaction  in  which one  moles  of  substance  in  its  standard state  is formed from  its constituent  element in  their  standard  state.All  the  substance must  be  in  their  most stable  state  at  100kpa  and  25  degrees  celsius.
therefore  for  HF is
1/2H2 +1/2F2 =HF
        
                    
             
        
        
        
Answer:
C) to show that atoms are conserved in chemical reactions
Explanation:
When writing a chemical reaction, we should always consider the Mass Conservation Law, which basically states that; in an isolated system; the total mass should remain constant, this is, the total mass of the reactives should be equal to the total mass of the products
For this case, we should add the apporpiate coefficients in order to be in compliance with this law:
2H₂ + O₂ → 2H₂O
So, we can check the above statement:
For reactives (left side):
4H
2O
For product (right side):
4H
2O
 
        
             
        
        
        
As the concrete has cement, gravel, crushed rocks, sand, and water of different physical state and can be separated by physical methods hence it should be called as a mixture. 
As the components have significant physical boundaries which clearly identify their presence, the mixture is heterogeneous and not homogeneous.
Thus this is a concrete is a heterogeneous mixture of cement, gravel, crushed rocks, sand, and water