13.
The growing plants need which of the following elements in largest quantity?
Answer : B. Nitrogen
14.
Rainwater helps to increase the __________ of the soil
Answer : B. nitrogen content
15.
the amount of nitrogen present in atmospheric air is
Answer : B. 78%
16.
Gammexane is the trade name of
Answer : A. BHC
17.
Which one of the following is used to kill rat
Answer : A. white phosphorus
18.
Copper sulphate is used as
Answer : B. Fungicide
