<span>Among important crop plants, nitrogen-fixing root nodules are most commonly an attribute of
B) legumes</span>
A. Oxygen ion
I am not sure but that's the right one I think. If I am wrong then I am sorry
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Option-C: They react mainly by substitution.
Explanation:
Alkene doesn't give substitution reactions because they are non polar in nature. The double bond in alkene is responsible for Electrophillic Addition reactions as it electron rich and nucleophilic in nature. Reaction of Alkene is given below,</span>
Losing eltron is the answer