Answer:
100 C or 212 F
Explanation:
That is the boiling point for liquid so both gas and liquid are presented. 
 
        
                    
             
        
        
        
Answer: Dissociation constant of the acid is  .
.
Explanation: Assuming the acid to be monoprotic, the reaction follows:
                          
pH of the solution = 6
and we know that
![pH=-log([H^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH%5E%2B%5D%29)
![[H^+]=antilog(-pH)](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3Dantilog%28-pH%29)
![[H^+]=antilog(-6)=10^{-6}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3Dantilog%28-6%29%3D10%5E%7B-6%7DM)
As HA ionizes into its ions in 1 : 1 ratio, hence
![[H^+]=[A^-]=10^{-6}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BA%5E-%5D%3D10%5E%7B-6%7DM)
As the reaction proceeds, the concentration of acid decreases as it ionizes into its ions, hence the decreases concentration of acid at equilibrium will be:
![[HA]=[HA]-[H^+]](https://tex.z-dn.net/?f=%5BHA%5D%3D%5BHA%5D-%5BH%5E%2B%5D)
![[HA]=0.1M-10^{-6}M](https://tex.z-dn.net/?f=%5BHA%5D%3D0.1M-10%5E%7B-6%7DM)
![[HA]=0.09999M](https://tex.z-dn.net/?f=%5BHA%5D%3D0.09999M)
Dissociation Constant of acid,  is given as:
 is given as:
![K_a=\frac{[A^-][H^+]}{HA}](https://tex.z-dn.net/?f=K_a%3D%5Cfrac%7B%5BA%5E-%5D%5BH%5E%2B%5D%7D%7BHA%7D)
Putting values of ![[H^+],[A^-]\text{ and }[HA]](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%2C%5BA%5E-%5D%5Ctext%7B%20and%20%7D%5BHA%5D) in the above equation, we get
 in the above equation, we get


Rounding it of to one significant figure, we get

 
        
             
        
        
        
D is the answer here look
 
        
        
        
2 elements from the periodic table