4. A rocklike copy of a plant, a feather, or a bone is a

FOSSIL

A rock-like copy of a plant,a feather,or a bone(natural things) is a FOSSIL

Explanation: Fossil can be defined as the preserved remains or trace or impression from a plant or animal that pre-existed in history or geological age,these remains are preserved in petrified form in the earth crust.

Fossils serves as the primary source of information about the history of life of a plant or animal on earth.

They are studied by archeologists.

The five types of fossils are; Carbon Fossils,Trace fossils, Body fossils, Molecular fossils and Pseudo fossils.

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

you know they are heterozygous for a trait because they have it as jj or jj.