Select the pairs that are correctly matched with the type of isomerism they illustrate. One or more options may be correct.

Exchange of ligands between two complex ions gives coordination isomerism (1 correct). A ligand bound through N or O gives linkage isomerism (2 correct). Exchange of an anion between the sphere and counter ion gives ionisation isomerism (4 correct). cis and trans differ in arrangement and neither is chiral, so that is geometrical isomerism, not optical (3 wrong).