Which of the following is not true?

Which of the following is not true?

The Kelvin scale starts at absolute zero.
The freezing point of mercury is -39° C.
Ice only has one melting point, but that point can be measured by different scales.
The Celsius scale is divided into 100 degrees between the melting and boiling points of water at sea level.
Freezing of water occurs at a single point, 0° C (32° F