The number of electrons outside the nucleus of element A is equal to the number of electron layers, which can be H, Be, al and other elements. Because the corresponding element A is gas, element A is H and element A is H2, the E generated by the reaction between a and b is liquid at room temperature, which should be H2O and element B is O2, so element B is O, while elements B and C belong to the same family, element C is element S and element D is a common metal, which can react with water at high temperature. According to the transformation relation B+C→ FBI, F is SO2, I is SO3, and J is H2SO4. The G generated by the reaction of Fe with S is FeS, L is FeSO4, M is H2S, and K is Fe2(SO4)3. H2S reacts with Fe2(SO4)3 to generate S, H2SO4 and FeSO4.

(1)E is H2O, m is H2S, o is nonmetal, and there are hydrogen bonds between water molecules, so the answer is: there are hydrogen bonds between water molecules, so the boiling point of water is higher than H2S;

(2) Elements A and B can form two compounds, one of which contains four nuclei and the structural formula is H-O-O-H, so the answer is H-O-O-H;

(3) The chemical equation of high temperature reaction between E (H2O) and D(Fe) is 3Fe+4H2O(g)? High temperature? . ? Fe3O4+4H2, H2S reacts with Fe2(SO4)3 to generate S, H2SO4 and FeSO4, and the ionic equation of the reaction is 2Fe3++H2S=2Fe2++S↓+2H+.

So the answer is: 3Fe+4H2O(g)? High temperature? . ? fe3o 4+4h 2； 2fe 3 ++ H2S = 2fe 2 ++ S↓+2H+；

(4)L is FeSO4, which is easy to be oxidized. In order to prevent Fe2+ from being oxidized, a small amount of Fe can be added. The method of detecting cations in FeSO4 _ 4 aqueous solution in laboratory is to take a small amount of solution in a clean test tube and add a few drops of KSCN solution, and there is no phenomenon. Then add chlorine aqueous solution to turn blood red, which proves that there is Fe2+.

So the answer is: prevent Fe2+ from being oxidized; ? Take a little solution in a clean test tube, add a few drops of KSCN solution, there is no phenomenon, and then add chlorine solution to turn blood red, which proves that there is Fe2+;

(5) It is known that under certain conditions, every1mol of SO2 and O2 completely react to generate 98.0kJ of I heat, then 2molSO2 SO2 and O2 completely react to generate 196.0kJ of I heat.

If 2mol SO2 reacts with 1mol O2 under these conditions, and the heat released at equilibrium is 176.4kJ, the conversion rate of SO2 is176.45438+096x100% = 90%.

If the temperature and pressure are kept constant (the reaction mixture is gas), the amount of each substance when it reaches equilibrium is the same as the above-mentioned equilibrium state. The added substance should be transformed into the starting substance, and the amount of the substance should meet the requirements of 2mol SO2 and 1mol O2, and only ③ can meet the requirements.

So the answer is: 90%; ③.