Answer:
1st one is the answer water cannot be purified by nature pls add me in brainliest
Answer: The bold staircase in the periodic table allows us to classify which elements are metalloids.
Explanation: Additionally, it acts like a "divider" that allows us to properly distinguish the metals from the non-metals in the periodic table.
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Answer:
No moon has no light.
Explanation:
It only reflects the light coming from the sun. Only star produces light and moon is a satellite that revolvs around the earth.
Electrons is located outside the nucleus
Answer:
meter the mean free path of hydrogen atoms in interstellar space.Explanation:
The mean free path equation is given as:

Where"
d = diameter of hydrogen atom in meters
n = number of molecules per unit volume
We are given: d = 100 pm = 



meter the mean free path of hydrogen atoms in interstellar space.