The shadow zone exists because: O A. sunlight blocks out S waves in certain regions.
B. seismic waves cannot travel through liquids.
C. P waves reflect as they travel through Earth.
O D. the mantle and core are composed of different material.

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?

As changes in energy levels of electrons increase, the frequencies of atomic line spectra they emit

How many atoms or molecules are there in a mole of a substance?