Câu 25: Đốt cháy hoàn toàn 5,6 lít khí etilen ở đktc. Thể tích khí oxi và thể tích không khí cần dùng ở đktc là ( biết rằng khí oxi chiếm 20% thể tích không khí) A. 22,4 lít; 112 lít. B. 33,6 lít; 68 lít. C. 16,8 lít; 84 lít. D. 11,2 lít; 56 lít. Câu 26: Hợp chất C3H6 có bao nhiêu công thức cấu tạo dạng mạch vòng ? A. 2 B. 1 C. 3 D. 4 Câu 27: Nung hoàn toàn hỗn hợp 2 muối CaCO3 và MgCO3 thu được 76 gam hai oxit và 33,6 lít CO2 (đktc). Khối lượng hỗn hợp muối ban đầu là : A. 124 gam B. 141 gam C. 142 gam D. 140 gam Câu 28: Cặp chất nào sau đây không thể tồn tại trong dung dịch? (do tác dụng được với nhau) A. Ca(OH)2 , Na2CO3 B. Ca(OH)2 , NaCl C. NaOH , KNO3 D. Ca(OH)2 , NaNO3 Câu 29: Hấp thụ hoàn toàn 2,24 lít khí CO2 (đktc) vào dung dịch nước vôi trong có chứa 0,075 mol Ca(OH)2. Muối thu được sau phản ứng là: A. Ca(HCO3)2 B. CaCO3. C. CaCO3 và Ca(HCO3)2 D. CaCO3 và CaHCO3.

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