Which of the following has the largest population in a food chain?

Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time?

Read the given statements and determine how many of them are correct.
$(1)$ Secondary succession depends on the condition of the soil and the availability of water.
$(2)$ Air,water,and land are abiotic factors of an ecosystem.
$(3)$ The structure of an ecosystem includes the cycling of nutrients and the unidirectional flow of energy.
$(4)$ The primary source of energy in an ecosystem is the sun.

How many statements are correct?
$(a)$ Some animals like cockroaches,crows,etc.,are omnivores.
$(b)$ Detritus food chain $(DFC)$ begins with dead organic matter.
$(c)$ Each trophic level has a certain mass of living material at a particular time called as standing crop.
$(d)$ Species composition and stratification are two main structural features of an ecosystem.

How many food chains are there in the food web shown above?

Which of the following processes occurs at a faster rate?