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490 n  f=125n a=2.5m/s2

Is there any opitions? if you have the periodic table, the noble gases are 8a family, the halogen are the 7a family, and the nonmetal are  carbon, nitrogen, phosphorus, oxygen, sulfur, selenium, fluorine, chlorine, bromine, iodine and astatine.

Answer///(d) atoms contain small,negatively charged particles;

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