Which compound releases a reddish brown gas on reaction with concentrated sulphuric acid and copper turnings?What is the middle region of the blast furnace called?What happens when sulphur dioxide is passed through bromine water?What is the equation for the reaction between carbon and carbon dioxide?Why is sulphur dioxide used as an antichlor?What test is used to distinguish Iron(III) chloride from copper chloride?

Dear student kindly post your questions one by one.
1.The compound which releases reddish brown gas on reaction with conc.H2SO4 and Cu turnings is copper nitrate,Cu(NO3)2.This brown gas released is NO2.
2.The middle region of blast furnace is called as slag formation zone.In this region limestone,CaCO3 decomposes to form CaO which combines with silica to form Slag.
3.It is observed that SO2 is passed through bromine water the red colour of bromine water disappears.
4.Kindly check this question again.
5.An antichlor is a substance that removes excess chlorine to stop a bleaching reaction.Sulphur dioxide acts as a reducing agent, which reduces halogens to hydrogen halides.
SO2+2H2O+Cl2→2HCl+H2SO4.
6.When NaOH is added,it is observed that iron(III) chloride forms reddish brown ppt.which is insoluble in excess of NaOH.On the other hand copper chloride forms blue ppt.which is insoluble in excess of NaOH.