A can cause extinctions by causing the blocking of sunlight

A. rise in sea level
B. volcanic eruption
C. shift in earths plates

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

geologic time scale (for gradpoint) =)

not: both offer magnification to the atomic level.

if someone had the list of traits you provided