Q. What difference does it make when a mixture of iron fillings and sulphur
(i) is crushed hard.
(ii) is heat till red hot

Dear Student,

3.(i) When A mixture of Iron Fillings and Sulphur are Crushed hardly, it will make no difference as it is still a mixture (because there is no Chemical change going on).
  (ii) On heating the mixture of iron filings and sulphur, sulphur melts and reacts exothermically to form Iron (II) Sulphide. The reaction is shown below:
                                                          $8\mathrm{Fe}\left(\mathrm{s}\right) + {\mathrm{S}}_8 \left(\mathrm{s}\right) \stackrel{\mathrm{Strong} \mathrm{Heating}}{\to } 8\mathrm{FeS} \left(\mathrm{s}\right)$
Hope this information clears your doubts about the topic.

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