Question

select all the elementary substances.
bromine (br₂)
nickel (ni)
hydrogen (h₂)
copper (cu)

Explanation:

An elementary substance is a pure substance composed of only one type of atom. Bromine (\(Br_2\)) is a diatomic molecule of the element bromine. Nickel (\(Ni\)) is a metallic element. Hydrogen (\(H_2\)) is a diatomic molecule of the element hydrogen. Copper (\(Cu\)) is a metallic element. All of these are composed of only one type of atom, so they are elementary substances.

Answer:

All the given substances (bromine (\(Br_2\)), nickel (\(Ni\)), hydrogen (\(H_2\)), copper (\(Cu\))) are elementary substances.