化学题1(国外英文资料).docVIP

化学题1(国外英文资料) Thats probably all. Special chemistry training for grade nine - chemistry calculation I. calculation of chemical formulas In the mixed gas composed of 1.CO and X, the mass fraction of oxygen element is 55%, and X is the following () substance A, CO2, B, NO2, C, SO2, D, SO3 2. a mixture of MgO and another metal oxide 4G, known as the oxygen containing element 1.8g, another metal oxide is () A, CaO, B, Fe2O3, C, Al2O3, D, CuO In the 3. compounds X2Y and YZ, the mass fraction of Y element is 40% and 50%, respectively, and the mass fraction of Y in compound X2YZ3 is () A, 45% B, 25% C, 20% D, 16.7% In the mixture of 4.FeSO4 and Fe2 (SO4) 3, the mass fraction of sulfur is a%, and the mass fraction of iron is () A, 1 - a%, B, 1 - 3a%, C, 2a%, D, 3a% In the mixture of 5.KCl and MgCl2, the ratio of potassium to magnesium atoms is 2:1, and the mass fraction of MgCl2 in the mixture is () A, 56% B, 38.9% C, 30% D, 78% 6., there is a mixture of Mg and MgO. The oxygen content of the sample is 32%, and the magnesium element is considered A, 20% B, 40% C, 48% D, 80% 7. in the mixed gas of O2 and SO2, the mass fraction of oxygen element is 60%, and the mass ratio of O2 to SO2 in the mixture is () A, 1, 1, B, 2, 1, C, 1, 4, D, 1, 2 The 8. elements x and Y constitute two compounds A and B, and X elements in A account for X elements in B. The chemical formula of A and B compounds composed of X and Y are () A, xY, xY2, B, x2Y, x2Y3, C, xY2, x2Y, D, xY3, x2Y4 9., one of the effective measures to reduce the greenhouse effect is a large number of afforestation. Photosynthesis of green plants in the presence of chlorophyll is an important link to complete the carbon dioxide cycle. The relative molecular mass of known chlorophyll is less than 900, and its molecule contains C73.8% (below mean mass fraction), H8.3%, N6.3%, Mg2.7%, and the rest is O.. The chemical formula of chlorophyll is determined. Two. Calculation of Solutions 1.5g a substance is completely dissolved in 95g wa