Umm I think it might be a b c in order?
        
             
        
        
        
Answer:
Na2SO4 is equal to 0.0070401642780093 mole.
Explanation:
 
        
             
        
        
        
In order to properly measure the displacement, the object must be completely submerged, however in the diagram the wood is floating. So the measured displacement will only be a fraction of what it actually is.
 
        
             
        
        
        
Answer:
Option B. 2096.1 K
Explanation:
Data obtained from the question include the following:
Enthalpy (H) = +1287 kJmol¯¹ = +1287000 Jmol¯¹ 
Entropy (S) = +614 JK¯¹mol¯¹
Temperature (T) =.? 
Entropy is related to enthalphy and temperature by the following equation:
Change in entropy (ΔS) = change in enthalphy (ΔH) / Temperature (T) 
ΔS = ΔH / T
With the above formula, we can obtain the temperature at which the reaction will be feasible as follow:
ΔS = ΔH / T
614 = 1287000/ T
Cross multiply 
614 x T = 1287000
Divide both side by 614
T = 1287000/614
T = 2096.1 K
Therefore, the temperature at which the reaction will be feasible is 2096.1 K