It is a mixture because the compounds that make up air e.g. oxygen (o2), Carbon dioxide (co2) and the most important Nitrogen which is an element and makes up 78.09% of air are not chemically bound in the way that compounds are because they can be separated easily and there has been no change in state to any of the compounds or elements in air!hope this helpful! 
 
        
                    
             
        
        
        
As,
                           5471 kJ heat is given by  =  1 mole of Octane
Then,
                    5310 kJ heat will be given by  = X moles of Octane
Solving for X,
                                  X  =  (5310 kJ × 1 mol) ÷ 5471 kJ
                                  X  =  0.970 moles of Ocatne
So, 0.970 moles of Octane will liberate 5310 kJ energy. Now changing moles to mass,
As,
                                  Moles  =  mass / M.mass
Or,
                                  Mass  =  Moles × M.mass
Putting values,
                                  Mass  =  0.970 mol × 114.23 g/mol
                                  Mass  =  110.83 g of Octane
        
             
        
        
        
<h2>Answer:</h2>
She should notify her teacher.
<h2>Explanation:</h2>
Sodium Hydroxide is very corrosive in nature and it causes Redness, Pain, Serious skin burns and Blisters. Sodium hydroxide does not produce systemic toxicity, but is very CORROSIVE and can cause severe burns in all tissues that it comes in contact with. Therefore she should not touch it and she must notify her teacher as soon as possible.
 
        
        
        
Answer : The molar heat of solution of KCl is, 17.19 kJ/mol
Explanation :
First we have to calculate the heat of solution.

where,
q = heat produced = ?
c = specific heat capacity of water = 
 = change in temperature = 0.360 K
 = change in temperature = 0.360 K
Now put all the given values in the above formula, we get:


Now we have to calculate the molar heat solution of KCl.

where,
 = enthalpy change = ?
 = enthalpy change = ?
q = heat released = 460.8 J
m = mass of  = 2.00 g
 = 2.00 g
Molar mass of  = 74.55 g/mol
 = 74.55 g/mol

Now put all the given values in the above formula, we get:


Therefore, the molar heat of solution of KCl is, 17.19 kJ/mol
 
        
             
        
        
        
<span>Ionic bonding between sodium and phosphate ions.</span>