1. two atoms are the same element if they have the same
a. atomic number
b. number of neutrons
c. charge
d. number of electron shells

Same number of neutrons.

Explanation:

What defines an atom as a certain element is the number of neutros in its nucleus. Some atoms have a different number of neutrons, but are still the same element, we call these variants "isotopes".

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BiologiaMagister

Two atoms are the same element if they have the same atomic number

Option A

Explanation:

The atomic number of an element is defined as the number of protons or electrons of an element. This signature of sub atomic particles is distinct for each element. No 2 elements have the same atomic number.

Sometimes the properties of elements are attributed towards arrangement and number of protons and electrons of an element. The elements are arranged according to their atomic number in a periodic table.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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b tumor cells have a cell wall instead of a membrane

explanation:

tumor cells different from normal cells because tumor cells have a cell wall instead of a membrane.