Isoelectronic species are ions or elements that have equal number of electrons. From the root word, electron of the word isoelectronic. On the other hand, isotructural species are compounds with the same structures.Hope this answers the question.
Given :
Number of He atoms, 
atoms.
To Find :
How many grams are their in given number of He atoms.
Solution :
We know, molecular mass of He is 4 g. It means that their are 
atoms in 4 g of He.
Let, number of gram He in 
atoms is x , so :
Therefore, grams of He atoms is 22.58 g .
The volume measured using such a cylinder will be reported to the nearest 10th mL.
<h3>Cylinder graduation</h3>
10 mL graduated cylinders are always read to the nearest two decimal places.
100 mL graduated cylinders are always read to the nearest 1 decimal place. The nearest 1 decimal place is the same thing as the nearest 10th.
Thus, a reading made using a 100mL increment graduated cylinder would be reported to the nearest 10th mL.
More on cylinder graduation can be found here: brainly.com/question/14427988
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Answer:
The experimenter observed this experiment in a lab rather than natural world because it might be dangerous to the atmosphere if he does the experiment in the natural world and it was still an hypothesis so that's why he did it in the lab.
