Question

a pure solid sample of substance x is put into an evacuated flask. the flask is heated at a steady rate and the temperature recorded as time passes. here is a graph of the results:
temperature (°c)
heat added (kj/mol)
use this graph to answer the following questions:
what is the boiling point of x?
☐ °c

Explanation:

Step1: Identify boiling phase

Boiling occurs when temperature is constant during heating (flat segment in heating curve, after melting).

Step2: Read temperature at boiling

From the graph, the flat segment (boiling) has temperature around 150 °C (checking the y - axis for the horizontal part after the first flat (melting) and the rise, the second flat is at ~150 °C).

Answer:

150 (assuming the graph's horizontal segment for boiling is at 150 °C; exact value depends on graph scale, but typical from the plot shown, the boiling point flat is at 150 °C)