What do element; atoms; molecule; chemical bond; compound; mixture; and substance have in common

If a solution had a ph of 7 what is the solution

Water is initially present in a state where its molecules are far apart. during a change of state, its molecules slow down. which change of state has most likely taken place? from a gas to a liquid from a liquid to a gas from a solid to a liquid from a gas to a plasma

Why is the melting of ice a physical change ?