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    Which compound gives a lilac colour in a flame test and does not decompose on heating?

    A) Potassium Bromide
    B) Potsassium Nitrate

    Can anyone tell me why the answer is not B? Because I thought so that group 1 nitrates are thermally stable so that’s why I chose A. (which is wrong)

    Let’s imagine we know nothing about how stable these are - what *could* KBr decompose into? Compare this with KNO3, with quite a few nitrogen and oxygen atoms. You’re right that potassium nitrate doesn’t decompose easily, but, compared to potassium bromide, it’s way more likely!
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Updated: October 23, 2017

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