NaHCO3 can be used in :
baking powder
as mild antiseptic
fire extinguisher
all of these
As we learnt ,
Uses of NaHCO3 -
1)In baking powder
2) In pharmaceutical industries (mild antiseptic)
3) Fire extinguishers
All of given options are the uses of NaHCO3 .
Therefore, option(4) is correct.