A material was cooled from 100 ◦C to 20 ◦C. What was the change in temperature?

What phase of matter has particles that are held together but can flow past each other and takes the shape of a container, filling it from the bottom up?

How many neutrons does a atom of cobalt have?

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false