Which of the following is definitely true about the kingdom, Protista. A. They always have a cell wall

B. They always have a nucleus

C. They are always unicellular

D. They are always heterotrophs

B. They always have a nucleus

Explanation:

The organisms belonging to kingdom Protista are single-celled- means they are unicellular and they have a well-defined nucleus enclosed in a nuclear membrane. Hence, they are eukaryotes. So the correct option is B.

B. They always have a nucleus

Explanation:

Protista always has a nucleus. So, option (B) is the correct answer.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.