<prompt> Antigen antibody precipitation is maximally seen in which of the following ?Excess of antibodyExcess of antigenEquivalence of antibody and antigenAntigen Hapten interaction  <response>: According to lattice hypothesis, precipitation results when a large lattice is formed consisting of alternating antigen and antibody molecules. This is possible only at the zone of equivalence. At the zone of equivalence, antigen and antibody are in optimum propoion. Lattice formation and visible reactions are enhanced. Reference: Anathanarayan panikers 9th edition, pg no:105 p 