A graduated cylinder has a mass of 55g when empty. When 32 mL of water is added, the graduated cylinder has a mass of 122 g. If a rock is added to the graduated cylinder, the water level rises to 75mL and the total mass is now 250g. What is the density of the rock?

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

Which of the following has wavelength longer than the wavelength of viable light? a) x rays b) gamma rays c) radios waves d) ultraviolet waves

Helium decays to form lithium. which equation correctly describes this decay?