<span>we know that each
element has an unique spectra and it can be used to identify the
element. it shows that the energy levels of the electrons and different colors are the result of different wavelengths.
hope it helps
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1 is D - double-replacements do not make solid metals
2 is A - to have complete combustion the original compound must ONLY have C, H and O
3 is B - the elemental Mg replaces the H in the HCl
<h2>YOUR ANSWER Is number of istopes</h2>
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