What is heat of vaporization?
a. it is the heat required to change a substance's temperature by 1°c.
b.
it is the heat required to change a gram of substance from a solid to a liquid.
c.
it is the heat required to change a substance from a solid directly to a gas.
d.
it is the heat required to change a gram of substance from a liquid to a gas.
e. it is the heat required to separate one substance into two substances.