Below earth's surface heat is transferred in large convection currents within melted rock. Within these currents A. cooler rock rises and hotter rock sinks
B. hotter rock rises and cooler rock sinks
C. hotter and cooler rock sink but do not rise
D. cooler and hotter rock rise but do not sink

How is the composition of a meteorite relevant to finding out the composition of earth's core?

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

Voltaic cells produce a positive overall charge. what does this indicate? a. the reaction is likely to be endothermic. b. the reaction is spontaneous. c. the reaction is not likely to occur. d. the reaction is not spontaneous.