The kw of water varies with temperature. calculate the ph of water at 46⁰c with a kw = 1.219 x 10-14. show all calculations leading to an answer.

Kw is equal to the concentration of the H+ and the OH-. In pure water, the concetration of H+ and the OH- is equal. In computing for the pH of water, we tke the negative log of the concentration of H+. To solve the concentration of H+ we take the square root of the Kw (Since Kw=[H+]*[H+] since [H+]=[OH-]) 
H+ is equal to 1.104*10^-7
negative log of the H+ conc. or the pH is 6.96 (pH = -log(1.104*10^-7))

The answer is valid and is close to the neutral pH which is 7. 

Ais the correct answer

They carry out the exchange of gases as we breathe ( oxygen and carbon dioxide).