The number of capsomeres in a $T_4$ bacteriophage is:

Assertion $(A)$: Viruses are considered as a link between living and non-living things.
Reason $(R)$: Viruses are inactive and behave like non-living matter in a free state,whereas they show active and living behavior inside a host cell.

Which of the following lacks a capsid?

Which is correct $w.r.t.$ lichens?

They are pollution indicators and never grow in polluted areas.

Which of the following is the use of lichens in the context of pollution?