Which involves a chemical change? filtering sand from water

distilling pure water from salt water

separating hydrogen and oxygen from water

evaporating sugar from sweetened water

explanation:

considering the bohr theory, the type of connection that requires the transfer the answer conuldn't be right

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.