Cho luồng khí H2 dư đi qua ống nghiệm đựng 50 gam hỗn hợp gồm Fe3O4 và CuO, Fe2O3 đun nóng đến khi PỨ xảy ra hoàn toàn. Khí và hơi thoát ra khỏi ống cho hấp thụ vào 100g dung dịch Ca(OH)2 5% thì nồng độ dung dịch thu đc giảm còn 4.5%. Tính khối lượng kim loại thu đc sau PỨ

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