Variations in the Earth's orbital rotation have caused major changes in the history of Earth's climate. These types of changes
are caused by
-natural processes.
-human activities.
-natural processes and -human activities.
-population cycles.

An unknown substance is a white solid at room temperature and has a melting point of 78 °c. which of the following substances is most likely to be the identity of the unknown sample? a. naphthalene, a molecular solid with the formula c10h8 b. silica, a network solid held together by covalent bonds with the formula sio2 c. calcium chloride, an ionic compound with the formula cacl2 d. water, an molecular compound with the formula h2o