What is a contour interval?
a. a loop formed by contour lines that indicates a peak or depression
b. the elevation difference between two adjacent contour lines
c. an imaginary line that joins points of equal elevation
d. the degree of a slope's steepness

In order for a high temperature boiler or steam engine to produce superheated water, or steam: the heat source must be greater than 100°c the water must be permitted to evaporate quickly the system must be sealed and become pressurized above atmospheric pressure the vapor pressure must be kept below 760 mm(hg)