“Is a percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element.” < you can try and put it in your own words or you could stick with that just add quotations :)
Answer : The expected coordination number of NaBr is, 6.
Explanation :
Cation-anion radius ratio : It is defined as the ratio of the ionic radius of the cation to the ionic radius of the anion in a cation-anion compound.
This is represented by,

When the radius ratio is greater than 0.155, then the compound will be stable.
Now we have to determine the radius ration for NaBr.
Given:
Radius of cation,
= 102 pm
Radius of cation,
= 196 pm

As per question, the radius of cation-anion ratio is between 0.414-0.732. So, the coordination number of NaBr will be, 6.
The relation between radius ratio and coordination number are shown below.
Therefore, the expected coordination number of NaBr is, 6.
Answer:
Explanation:
Observation. Observational skills are the starting point for critical thinking. People who are observant can quickly sense and identify a new problem.
Analysis. Once a problem has been identified, analysis skills become essential. ...
Isotopes of an element have same atomic number (number of protons) but vary in the mass number (number of neutrons). The chemical reactivity of an element is not affected by the change in mass number. So, for stable isotopes of Oxygen, (Oxygen-16, Oxygen-17 and Oxygen-18) the biochemical pathway of oxygen breathed in during respiration remains unaffected even with different isotopes. Only the radioactive isotopes of oxygen when breathed in may cause serious health hazards as they emit radiations that may damage the internal organs in the body.