The answer would be step three but not positive this is correct hope this helps
A mixture of charcoal, sand, sugar, and water is a heterogeneous mixture. Sugar can easily dissolve in water. Slightly heating the mixture will ensure all of the sugar is dissolved in the water. The mixture then can be filtered to separate out sugar solution from sand and charcoal. The mixture of sand and charcoal is washed several times with water and filtered so that no traces of sugar solution remain in the mixture. To the mixture containing sand and charcoal, water is added. Charcoal being lighter floats on the surface of water, whereas sand being heavy sinks to the bottom. The charcoal floating can be removed manually. After all the charcoal is removed, the mixture of sand and water is again filtered and the sand collected on filter paper is dried. Therefore, by using the above process sand can be separated out from a mixture of charcoal, sand, sugar, and water.
The standard state formation reaction is a chemical reaction in which one moles of substance in its standard state is formed from its constituent element in their standard state.All the substance must be in their most stable state at 100kpa and 25 degrees celsius.
therefore for HF is
1/2H2 +1/2F2 =HF
