nêu phương pháp hóa học phân biệt các chất sau , viết các PTHH nế có : a) các chất khí : CO2 , Cl2 , O2 , HCL b) các kim loại : nhôm , sắt , đồng c) cá dung dịch : HCl , H2SO4 , H2O , NaOH , NaCl

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