Neem and turmeric powders are often used in grain storage.
$(i)$ What are they called?
$(ii)$ What is the purpose of using neem and turmeric?
$(iii)$ What are herbicides?

(N/A) $(i)$ They are called bio-pesticides.
$(ii)$ The purpose of using neem and turmeric is to protect stored grains from pests such as insects,rodents,fungi,mites,and bacteria.
$(iii)$ Herbicides are chemical substances used to remove or control weeds in cultivated fields during the early stages of crop growth.