When the external pressure is 505 kPa, what is the vapor pressure of water at its boiling point? Chemistry When the external pressure is 505 kPa, what is the vapor pressure of water at its boiling point? a. 0 kPa b. 101.3 kPa c. 505 kPa d. 1010 kPa Answer: C Learn More : Share this Share on FacebookTweet on TwitterPlus on Google+