what happens when a burning matchstick is brouth near the mouth of the test tube in which a metal reacted with sulphuric acid ??????
When a matchstick is brought near the mouth of the test tube in which a metal has reacted with sulphuric acid, the matchstick produces a pop-sound nd stops burning. this is due to evolution of hydrogen gas after the reaction.
METAL + ACID ---------> SALT + HYDROGEN GAS
eg. Zn + H2SO4 ----------> ZnSO4 + H2
THE POP SOIND MADE IS DUE TO THE EVOLUTION OF HYDROGEN GAS, THEREBY, BURNING OUT THE FLAME.
HOPE IT HELPS!