Some are autotrophic in nature: Correct. Monerans can be photoautotrophic (cyanobacteria) or chemoautotrophic.

Vacuoles are absent in cytoplasm: Correct. Monerans are prokaryotes and lack membrane-bound organelles, including true vacuoles.

They are ubiquitous: Correct. Monerans are found in nearly all environments (omnipresent).

Reproduction is mainly through sexual reproduction: Incorrect. Reproduction in Monera is primarily asexual, mostly through binary fission or budding. While genetic recombination (like conjugation) occurs, it is not considered true sexual reproduction.