question_answer

A student added \[10\,\,ml-12\,\,ml\] of Conc. \[{{H}_{2}}S{{O}_{4}}\]in a test tube containing \[5\,\,g-6\,\,g\] of sugar crystals and warmed it gently. He noticed that white crystals slowly turned brown and became a black mass. What happened in this change?

A)  \[{{H}_{2}}S{{O}_{4}}\] turned black but no change took place.

B)  Sugar got charred by the action of hot. conc. \[{{H}_{2}}S{{O}_{4}}\]and a chemical change took place.  

C)  It is only a physical change.

D)  It is an irreversible physical change.