Why do scientist use physical model of a plant cell instead of studying a cell directly

Explanation:

the purpose of scientific modeling varies.for example three dimensional helix model of DNA are used to visualize a object or system often being created from experimental data.Other models are intended to describe an abstract or hypothetical behaviour or phenomenon

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds