Câu 21: Tất cả các kim loại trong dãy nào sau đây tác dụng được với H2O ở nhiệt độ thường? A. Fe, Zn, Li, Sn B. Cu, Pb, Rb, Ag C. K, Na, Ca, Ba D. Al, Hg, Cs, Sr Câu 22: Phản ứng nào dưới đây là phản ứng thế: A. 2KClO3 - > 2KCl + O2 B. SO3 +H2O - > H2SO4 C. Fe2O3 + 6HCl - >2FeCl3 +3 H2O D. Fe3O4 + 4H2 -> 3Fe + 4H2O

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