Question

how pickle in aluminium jar is spoiled by hydrogen gas

Answer 1

Pickle is sour in taste so it has acid and also aluminium is metal as u myt knw d reax Acid+Metal>salt + hydrogen gas . The formation of this h2 change the pickle in harmful substance

Answer 2

As pickle is an acid and aluminum is a metal and metals react with acids to produce hydrogen gas, it is not advisable to store lemon pickle in an aluminum utensil because it will spoil the pickle and holes will be formed in the vessel.
metals reacts with acids vigorously to form metallic chlorides,which acts as a poison for human body thats why lemon being citric acid cant be stored in aluminium utensils