What does the symbol Pt mean in a chemical equation over the arrow in chemistry?

The dispersed phase is liquid and dispersed medium in milk is liquid

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

C) electrons encircling a nucleus with neutrons and protons

A.(nh4)(2co3)is the correct answer