Question

a plastic cube is released in water will it sink or come to the surface of water

Answer 1

It depends upon which plastic Material is used to make the cube. If it’s made form some polyolefin plastics such as LDPE, HDPE, LLDPE or PP than it will float as these materials has density less than 1. But most of the other plastic materials such as ABS, Nylon, PVC etc will sink in water as they have density of more than 1