What has a mass number of 60 and electron number of 30?

How many cells are our body made of ? ♡

Use the drop down menus to match each example to the fossil topic discussed then to show how the fossil record gives evidence of evolution

The double bond between a carbon atom and two oxygen atoms (a molecule of carbon dioxide) has two characteristics. what are they? a.an ionic bond is formed between the oxygen and carbon atoms. b.four valence electrons are shared. c.two valence electrons are shared. d.valence electrons are shared between oxygen atoms.