At what temperature is the boiling point of this substance

Option (c) is the correct answer.

Explanation:

Boiling point is defined as the temperature at which vapor pressure of a liquid becomes equal to the vapor pressure of its surrounding atmosphere.

In the given graph, boiling point of given substance is at 120 degree celsius.

And the horizontal line at 120 degree celsius shows that the liquid and vapor form of substance are in equilibrium with each other.

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.