The compounds [Co(SO4 (NH3)5 ]Br and [Co(SO4 (NH3)5 ]Cl represent

1. Linkage isomerism
2. Ionisation isomerism

3. Coordination isomerism
4. No isomerism

Compounds having same molecular formula but different structural formula are known

as isomers. [Co(SO4 (NH3)5 ]Br and [Co(SO4 (NH3)5 ]).]CI have not same molecular

formula, Hence, they are not isomers.