. A student is given four solid samples labeled W, X, Y and Z. She is told that the solids
could be gold, lead (II) sulfide, silicon dioxide (quartz) and iodine. The results of her
investigation are: a) W is a good electrical conductor while X, Y and Z are not b) When the
solids are hit with a hammer, W flattens out, X shatters, Y is smashed into a powder and Z is
not affected c) When the solids are heated with a Bunsen burner, Y sublimes but X, W and Z
do not melt d) In treatment with 6M HNO3, X dissolves but there is no affect on W, Y or Z.
On the basis of these test results, identify the solids. (Show your reasoning)
W-is Gold,cause its metal,which can flattens out and conduct electric current Y-is iodine,cause only this compound can sublimate after heating,and can be powder after hiting Z- is quartz,cause its very strong compound and can not be broken by hammer X- PbS,cause it can react with HNO3 3PbS + 8HNO3 --> 3Pb(NO3)2 + 2NO + 3S + 4H2O