Which substance is an element? Which is a liquid? An element? Which substance is made of ions?

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1 Answer
May 27, 2017

Answer:

Which is an element? Well, that's the hardest proposition........

Explanation:

As far as we know #"B is a liquid."# #"D is an ion"#. #"C"# is probably a gas (e.g. #CO_2#). Presumably, #"A"# contains only the one type of particle, i.e. the one type of atom, and could thus be classified as an element.