What is the percent mass/volume (%m/v) of a solution that is made from putting 25.0 g of nacl in water to make 275 ml of solution?

Express the following number in scientific notation. 0.026890 =

Why are people not able to scuba dive in the deep part of the ocean

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