What do valleys on the surface of a planet or moon suggest about previous land features? A. the presence of water B. the constant bombardment of asteroids C. the presence of human life forms D. the presence of earthquakes

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom

Thermohaline circulation and gyres

Idon't see the pic?