Which amongst the following is not a pesticide?

Solution

Chemistry ma’am · 3 steps

Sort each chemical by what it kills: insects mean pesticide, weeds mean herbicide.

1. How NCERT groups them. In the environmental chemistry chapter, pesticides are the chemicals that kill insects and pests. Chemicals that kill weeds are listed separately as herbicides.

   Option	Chemical family	Kills	Group
   (a) DDT	organochlorine	insects such as mosquitoes	pesticide
   (b) Organophosphates	organophosphorus compounds, e.g. malathion	insects	pesticide
   (c) Dieldrin	organochlorine, related to aldrin	insects	pesticide
   (d) Sodium arsenite, Na₃AsO₃	inorganic arsenic salt	weeds	herbicide

2. The odd one out. DDT, organophosphates and dieldrin all appear in the pesticide list. Sodium arsenite appears in the herbicide list, next to sodium chlorate, NaClO₃.
3. So. The answer is (d). Sodium arsenite is a weedkiller, so by this classification it is a herbicide, not a pesticide.

The idea to keep. Remember the NCERT lists: pesticides are DDT, aldrin, dieldrin and organophosphates. Herbicides are sodium chlorate and sodium arsenite. Ask what the chemical is meant to kill.

Answer from the NTA final answer key. Solution by PrepWiser.