One molecule of N2O4 contains 
two nitrogen 
four oxygen
        
             
        
        
        
Answer:
+8 J/mol 
Explanation:
The following were obtained from the question:
Mole of the compound = 3 moles 
Heat Energy used = 24J
Hreaction =? 
The heat of reaction is the energy released or absorb during a chemical reaction. It is can obtained mathematically by the following equation:
Hreaction = Heat energy/mole 
With the above equation, we can easily find the Hreaction for the question given as follow:
Hreaction = Heat energy/mole 
Hreaction = 24J / 3mol
Hreaction = 8 J/mol 
Since the compound used the energy, the Hreaction is +8 J/mol 
 
        
             
        
        
        
Answer:
24 hours
Explanation:
The computation is shown below:
The needed mole of  is
 is 
= 5 ÷22.4 = n
Also 1 mole of  required four electric charge
 required four electric charge
Now the charge needed is 
= n × 4 × 96,500 C
= 4 × 96,500 × 5 c ÷ 22.4
= 86160.714 C
Now
q = i t
t = q ÷ i 
= 86160.714 C ÷ 0.995
= 86593.7 seconds
= 24 hours
Hence, the correct option is A. 
 
        
             
        
        
        
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