From the chemical eqn 
No of moles of N2O5 = Mass/ molar mass 
Molar mass = (14* 2) + (16 *5) = 28 + 90 = 118g. 
From the chemical equation 7.9g of NO2 reacts with 7.9 *2 g of N2O5. We have a 1 :2 mole ratio. Hence mass of N2O5 = 14.8g 
No of moles = 14.8/ 118 = 0.133 moles.
        
                    
             
        
        
        
The shells correspond with the principal quantum numbers (n<span> = </span>1<span>, </span>2<span>, </span>3<span>, 4 ...) Each shell can contain only a fixed number </span>of electrons. The first shell can hold up to two electrons<span>, the second shell can hold up to eight </span>electrons<span>, the third shell can hold up to 18 and so on.</span>
        
             
        
        
        
do you have a formulai can do this problem 
 
        
                    
             
        
        
        
Answer:
0.7515875 eV

Explanation:
f = Maximum frequency = 
h = Planck's constant = 
W = Work function = 2.52 eV
Converting to Joules

Maximum photon energy is given by

Maximum Kinetic energy is given by

Converting to eV

The maximum kinetic energy of electrons ejected from this surface is 0.7515875 eV

The range of frequencies for which no electrons are ejected is

 
        
             
        
        
        
Answer:
A single component that can’t be separated 
brainliest please ;)