4) Clouds usually form when O A) air temperature reaches the dewpoint
B) evaporation has warmed the surrounding air
C) relative humidity is 0%
D) condensation nuclei have been removed from the air

B evaporation has warmed the surrounding air

Because a model would make the investigation easier to understand

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