Alarge hole that opens up in the ground as a result of over pumping groundwater is a

It is called a sink hole I believe

air, water, heat and noise pollution can all be caused by producing and using technology. consuming resources - non-renewable resources, including precious metals like gold, are used to make technology

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