Outer space has volume but no mass and black holes have mass but no volume, explains Dr. Robert Walch, UNC Physics. The center of the black hole is the singularity where there is no volume.
Sublimation is common in several substances, including carbon dioxide and iodine.
Chill the thermometer with dry ice or liquid nitrogen, the mercury will coalesce or fuse together, explains Dr. John Beel, UNC Chemistry. Physical Science Activities for Grades 2-8, by Tolman and Morton, has several very good possibilities for you. A Guidebook of K-12 Activities, V.1, from Institute for Chemical Education contains a list. The value is undefined, explains Mike Smith, MAST Hotline. Earth's rotation represents the sidereal day and is measured with respect to distant stars.