Give the observation when each of the following is heated in a dry test tube. Also give balanced equations :
(a) `HgCO_(3) " " (b) NH_(4)NO_(2)`
(c ) `(NH_(4)Cl+NaNO_(3)) "mixture" " " (d) Pb(NO_(3))_(2)`

Explanation

`(a) HgCO_(3) overset(Delta)to Hg+CO_(2)uarr +(1)/(2) O_(2)uarr`
(b) `NH_(4)NO_(2) overset(Delta)to N_(2) uarr + 2H_(2)O uarr` (no solid residue)
(c )`NH_(4)Cl+NaNO_(3)("mixture") overset(Delta)to NaCl +N_(2)O uarr +2H_(2)O uarr`
(d) ` Pb(NO_(3))_(2) overset(Delta)to PbO+2NO_(2) uarr +(1)/(2) O_(2) uarr`