How did scientist discover that earths outer core is liquid

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.

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

Acamcorder has a power rating of 17 watts. if the output voltage from its battery is 7 volts, what current does it use?units: