The_ of an element tells how many particles are in the nucleus of each atom.

The mass number of an element tells us about the number of particles present in the nucleus of an atom

Explanation:

Nucleons are defined as the sub-atomic particles which are present in the nucleus of an atom. Nucleons are protons and neutrons.

Atomic number is defined as the number of protons or electrons that are present in a neutral atom.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Mass number = Number of protons + Number of neutrons

For Example:  Taking an isotope of chlorine, Cl-35

Atomic number = Number of protons = 17

Mass number = Nucleons = 35

Hence, the mass number of an element tells us about the number of particles present in the nucleus of an atom

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

the answer is: reproductively

i think i spelled it wrong lol

anyways hope i

-lavira: )