Question

why arrangements of trophic levels w.r.t.number and energy is pyramid in shape?

Answer 1

This is because energy decreases as we move onto the next level. The energy decreased can be calculated by the ten percent law.
With respect to number, the organisms at higher trophic levels are less in number.
Hence, it is illustrated in the form of a pyramid

Answer 2

it's the physics that explains how everything works: the best description we have of the nature of the particles that make up matter and the forces with which they interact. Quantum physics underlies how atoms work, and so why chemistry and biology work as they do.