Answer:
Haven't evaporated all of the water
Explanation:
One of the main sources of error that occur in a formula of a hydrate lab is that all of the water is not evaporated. We can see at the end of the video that half of the CoCl2 is a light blue colors and the other half is a dark blue color. This indicates that all of the water still has not been evaporated off, resulting in the actual mass of the salt to be greater than the predicted value.
D would be your best bet because evaporation occurs when water is heated, it then vibrates and then magic!
Solid water is less dense than liquid water.
