Question

A yellowish brown coloured compound 'X' is photosensitive material. On exposure to sunlight, it gives a greyish substance 'Y' and brown fumes of a gas 'Z'. Identify 'X', 'Y' and 'Z'. How will you obtain 'X' from nitrate salt of 'Y'?

Answer 1

A - AgBr
B - Ag(silver)
C - Br(bromine)

To obtain silver from silver nitrate displace it with copper
                    AgNO​3+Cu   =  CuNO3+Ag
Silver Bromide is used in black and white photography. OR
Dear


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.

Enjoy learning!!