<prompt> In case of cyanide poisoning, antidote of amyl nitrate is given. This is an example of:Receptor antagonismChemical antagonismPhysical antagonismPhysiological antagonism  <response>: Ans. b Chemical antagonismRef: Vasudevan Biochemistry, 8th ed. P 321 Chemical: A type of antagonism where a drug counters the effect of another by simple chemical reactionneutralization not binding to the receptor. Physiological: Two drugs act on two different types of receptor and antagonize action of each other. Competitive: Both drugs bind to same receptor. 