Answer in one word or one line.
Give the common name of $Periplaneta \text{ } americana$.

The visual unit of the compound eye of an insect is known as .....

Sexual dimorphism is observed in .....

Number of segments found in the body of an adult cockroach is

Which of the following statement$(s)$ is/are correct regarding cockroaches?
$(i)$ The body of the cockroach is segmented and divisible into three distinct regions - head,thorax and abdomen.
$(ii)$ Blood vascular system is of closed type.
$(iii)$ They are monoecious and both sexes have well developed reproductive organs.
$(iv)$ The development of $P. americana$ is paurometabolous,meaning there is development through nymphal stage.

What external changes are visible after the last moult of a cockroach nymph?