A unknown inorganic compound (X) gave the following reactions `:` (i) on heating 'X' gave a residue, oxygen and oxide of nitrogen. (ii) Addition of acetic acid and `K_(2)Cr_(2)O_(7)` to its aqueous solution give a yellow precipitate. (iii) Addition of NaOH to its aqueous solution first forms a white precipitate, dissolve in the excess of the reagent. Identify the compound (X) and write balanced equation for step (i),(ii), `&` (iii).

Explanation

`(i) Pb(NO_(3))_(2)overset(Delta)(rarr)2PbO+4NO_(2)+O_(2)`
`(ii) Pb(NO_(3))_(2)+2CH_(2)COOHrarr Pb(CH_(3)COO)_(2)+2HNO`
`2Pb(CH_(3)COO_(2))_(3)+K_(2)Cr_(2)O_(7)+H_(2)O rarr 2PbCrO_(4)darr +underset("yellow")(2CH_(3)COOK)`
`(iii) Pb(NO_(3))_(2)+2NaOHrarr underset("White")(Pb(OH)_(2)darr)+2NaNO_(3)`
`Pb(OH)_(2)+2NaOH rarr Na_(2)PbO_(2)+2H_(2)O`