What happends when :
(a) Aqueous solution of lead acetate and sodium sulphide are mixed with each,
(b) A few drops of sodium nitroprusside are added to the aqueous solution containing sodium suphide.
(c) An aqueous solution containing sodium iodide is treated with a few drops of `CS_(2)` followed by excess of chlorine water.
(d) Phoshorus is fused with sodium peroxide

Explanation

(a) A black precipitate of lead sulphide is formed.
`Na_(2)S + underset("Lead acetate")((CH_(3)COO)_(2) Pb rarr underset(("Black ppt")) (PbS )+ underset("Sod. Acetate")(2CH_(3)COONa)`
(b) The solution acquires a violet colour.
`Na_(2)S + underset("Sod. nitroprusside")(Na_(2) [Fe(CN)_(5)NO]) rarr underset(("violet colour"))(Na_(4) [Fe(CN)_(5) NOS])`
(c) The oily layer of `CS_(2)` acquires a violet colour. chlorine being more reactive than iodine displaces the same from the salt solution
`2NaI + Cl_(2) rarr 2NaCl + I_(2)`
(d) Sodium phosphate is formed on fusion.
`5Na_(2) O_(2) + 2P overset(("Fuse"))rarr underset("Sod. phosphate")(2Na_(3)PO_(4) + 2Na_(2)O)`