Which of the following is $NOT$ correct for prokaryotic organisms?

Which of the following statements about a bacterial cell is/are correct?
$(i)$ Mesosome is formed by the extensions of plasma membrane into the cell.
$(ii)$ The pili are elongated tubular structures made up of a protein.
$(iii)$ Flagellum is composed of filament,hook,and basal body.
$(iv)$ Ribosomes are about $30 \; nm$ by $50 \; nm$ in size.

In which organisms are prokaryotic cells found? Give information about the diversity of their shapes.

Gas vacuole,Single envelope system,Cytoskeleton,Non-cellulosic wall,Microfilaments,Cytoplasmic streaming,Lack of any cell organelles.
How many of the above features are associated with a prokaryotic cell?

Prokaryotic cells are characterized by the absence of:

Identify the error in the following sentence:
"In prokaryotic cell internal extension structure called mesosome."