Muddy water is an example of mixtures​

suspensions of heterogeneous mixtures from which some of particles settle with time.

Muddy water is an example of homogeneous mixture.

The correct answer is :15 protons and 15 electrons.

Explanation:

Atomic number of an elements tells us total number of protons present in the an atom. And as we know that atom is an electrically neutral sphere so, atomic number also tells us about the total numbers of electron present in an atom of an element.

Atomic mass of an element tells us about the total number of neutrons and protons present in the nucleus of an atom.

Phosphorous has atomic number of 15 which means that in single phosphorus atom there are 15 protons and 15 electrons.