~Gửi bạn~
(*) nt: nguyên tử (mik viết tắt)
`2`Fe `: 2` nt sắt
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`3H_2O` `:` `3` nt hiđro `+` `2` nguyên tử oxi
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`5NaCe` `:` `5` nt natri `+` nt ceri
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`4Cl` `:` `4` nt Clo