B, it's properly because of convection! Please, correct me if I'm wrong :>
A heterogenous mixture is one which does not have uniform properties throughout. This is likely to happen in a mixture of sand and water because sand does not dissolve in matter and will settle down.
No they do not. Water is denser than oil so it sinks to the bottom and the oil floats.
If the piston is facing towards the bottom of the container holding the cold water, the piston will not move. It will move wherever it is facing.
