As a substance changes phase from a gas to liquid to solid:
a- the spacing between molecules increases.
b- it's density generally increases.
c- the spacing between molecules is not affected.
d- it undergoes chemical change.

Both 1,2−dihydronaphthalene and 1,4−dihydronaphthalene may be selectively hydrogenated to 1,2,3,4−tetrahydronaphthalene. one of these isomers has a heat of hydrogenation of 101 kj/mol (24.1 kcal/mol), and the heat of hydrogenation of the other is 113 kj/mol (27.1 kcal/mol). match the heat of hydrogenation with the appropriate dihydronaphthalene.

The crust of earth may a- continets and ocean floors. b-continents only. c-layers of sedimentary rocks and continents. d-all of the above

As you watch a surfer ride a wave towards the shoreline, what is the shoreline? a) displacement reference b) reference point c) coordinate plane d) cartesian boundary