1. Common knowledge : Go to the right of periodic table, the atomic radius is decreasing
2. Flurine has 9 protons and lithium has 3 protons. you know that the electron is attracted with the centre of the atom, that's why more proton, more 'energy' that attract to the centre and that's why it make the shape of the atom is smaller
False, the radiation from food and medical procedures have very little consequences. The radiation from a nuclear power plant can kill people which makes it a very large problem if not contained properly.
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C. NO2 is covalent. Hope this helps!
