In an experiment, a thermometer is placed in a test-tube of hot liquid. The temperature reading of the liquid is recorded every half minute. The table shows the results. What is the melting point of the substance?
Time/minutes | 0.0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 | 6.5 | 7.0 | 7.5 |
Temperature/oC | 73 | 65 | 59 | 55 | 55 | 55 | 51 | 48 | 45 | 42 | 40 | 38 | 36 | 35 | 34 | 33 |