Cho khí co đi qua m gam hỗn hợp X gồm fe3o4 và cuo nung nóng. sau 1 thời gian thu được 31,2 gam chất rắn Z và 11,2 lít hỗn hợp Y (đktc).biết y có tỉ khối với h2 là 18.Tìm m a, cho toàn bộ lượng Z ở trên bào dung dịch h2so4 đặc nóng dư, sau khi kết thúc các phản ứng thu được 6,72 lít khí so2.Tinh thành phần trăm khối lượng mỗi chất trong X

The diagram below shows the different phase transitions that occur in matter. which arrow represents the transition in which dew is formed?

Avolleyball player hit a ball with a mass of 0.25 kg. the average acceleration of the ball is 15.5 m/s². how much force did the volleyball player apply to the ball? 62.0 n 3.87 n 62.0 m/s² 3.87 m/s²

Tooth enamel consists mainly of the mineral calcium hydroxyapatite, ca_10(po_4)_6(oh)_2. trace elements in teeth of archaeological specimens provide anthropologist with clues about diet and diseases of ancient people. students at hamline university measured strontium in enamel from extracted wisdom teeth by atomic absorption spectroscopy. solutions with a constant total volume of 10.0 ml contained 0.726 mg of dissolved tooth enamel plus variable concentrations of added sr. added sr find the concentration of sr in the 10 ml sample solution in parts per billion = ng/ml. find the concentration of sr in tooth enamel in parts per million = mu g/g.