Which scientist used cepheid variables to measure the distance to faint "nebulas" in our sky, proving they were actually whole other galaxies?

Match each vocabulary term to its definition. 1. electrons neutral subatomic particles found in the nucleus of the atom 2. neutron lowest energy position of an electron in an atom 3. photon the path of an electron around the nucleus of an atom 4. ground state negatively charged, subatomic particles 5. protons packet of energy of specific size 6. element substance with only one type of atom 7. orbital positively charged, subatomic particles found in the nucleus of the atom

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat

Frank just graduated from eighth grade. assuming exactly four years from now he will graduate from high school how many seconds does he have until his high school graduation