Do these objects sink or float?






Whether an object sinks or floats depends on its density. Everything is made of molecules. Molecules are tiny particles that can only be seen with a microscope. Some objects have molecules that are packed closely together. Others have molecules that are packed more loosely. This is density. Objects with tightly packed molecules are denser and sink. A paper clip or a penny is dense. Objects with more loosely packed molecules are less dense and float. Wood, cork or sponges float. 

Look at this link to know why this happens.

http://easyscienceforkids.com/all-about-sink-and-float/