Question

heating curve for water
temperature (°c)
180
140
120
100
80
60
40
20
0
-20
time (min)
1 2 3 4 5 6 7 8 9 10
at what temperature does the solid start melting?
-20°c
0°c
20°c
80°c

Explanation:

Step1: Observe the heating - curve.

The flat - part of the curve at the beginning represents the melting process.

Step2: Identify the temperature at the start of the flat - part.

From the graph, the temperature at the start of the flat - part (where melting begins) is 0°C.

Answer:

B. 0°C