Question

What will happen to a lighted candle if it is brought near the mouth of a jar containing hydrogen gas ?Represent the reaction

Answer 1

when we place a lighted candle near the mouth of the jar containing hydrogen gas a 'pop' sound is heard which is caused due to reaction of hydrogen with atmospheric oygen.
 
H2+O2------->2H2O

Answer 2

We hear pop sound due to hydrogen is react with oxygen

H2+ O2=2h2o