Question

wheat dough if left in the open after a few day start to emit a foul smell becames unit for use give reasons

Answer 1

this is because fungus starts to grow their  the fungus will secreate a slimy liquid to make it edible for them to abbsorb and thus produces foul smell

Answer 2

Fungus is present in the air when they they land on moist substances they germinate and grow creating a foul smell.