What is the melting point of the substance represented by the complete heating curve below? a line graph showing the heating curve of a substance being heated from the solid phase all the way to the gas phase. the substance starts at a temperature around 0°c and ends at a temperature around 70°c. first, there is an incline with a positive slope from 0°c to 20°c, followed by a horizontal region at 20°c. then there is another incline with a positive slope from 20°c to 60°c, followed by another horizontal region at 60°c. the end of the heating curve shows another incline with a positive slope from 60°c to 70°c.
a. 0°c
b. 20°c
c. 40°c
d. 60°c