D. 750 pretty sure it’s the answer
Answer:
50km
Explanation:
70km - 20km = 50 kilometers
In a neutral atom, the number of protons is equal to the number of electrons.
Given that the charge on the ion of the element is -1. This means that there is one electron more than the number of protons in the element.
The atomic number = Number of protons = 57 -1 = 56
Element with atomic number 56 is Barium.
Mass number of the element = Number of protons + Number of neutrons
= 56 + 80 = 136
So the identity of the species: 
Answer:
Eliminate the hazard. ...
Substitute the hazard with a lesser risk. ...
Isolate the hazard. ...
Use engineering controls. ...
Use administrative controls. ...
Use personal protective equipment.
Explanation:
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