Dear Student,
1) Bacteria - Unicellular (Escherichia coli)
2) Fungi - Multicellular (Mould, Mushroom) and Unicellular (Yeast)
3) Algae - Multicellular (Spirogyra, Kelp (brown algae)) and Unicellular (Chlorella, Chlamydomonas)
4) Protozoa - Unicellular (Plasmodium, Entomoeba)
5) Virus - can not be classified as unicellular or multicellular, as they lack cellularity or are do not have proper cell structure.
Therefore, Bacteria and protozoans are unicellular only.
Algae, fungi - Can be both unicellular and multicellular.
Virus - Are not either unicellular or multicellular.
Regards