Question

A light yellow coloured compound X is exposed to sunlight for sometime it turn into grey colour material .what is the name of X .predict the type of chemical reaction occurred in it.

Answer 1

Evolution of brown fumes of a gas on exposure to sunlight suggests, that the gas (Z) is Br2 and X must be the bromide salt of Y. Now, AgBr is the salt that decomposes on exposure to sunlight, into Ag (greyish coloured substance) and Br2 gas, according to the following reaction :

Therefore, X is AgBr and Y is Ag(s).

Now, AgBr can be obtained from AgNO3, by reacting it with KBr, where K displaces Ag from AgNO3 and Br displaces NO3 from AgNO3, as per the following reaction:

AgNO3 + KBr → AgBr + KNO3

Thus, X = AgBr

Y = Ag

Z = Br2

Hope this information is helpful.

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Answer 2

X is Silver Bromide.
It undergoes photochemical decomposition.
2AgBr(s) ----> 2Ag(s) + Br2(g)
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