This garden pea plant is (a true line, not a true line) for the trait of pea shape, and is (homozygous, or heterozygous) for the gene determining the pea shape trait.

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