`NO_(2)` a red -brown poisonous gas is prepared in the laboratory by heating

Options

A. `NaNO_(3)`
B. `NH_(4)NO_(3)`
C. `Pb(NO_(3))_(2)`
D. `KNO_(3)`

Answer

C

Explanation

Nitrogen dioxde is prepared in the laboratory either by heating nitrates of heavy metals
`2Pb(NO_(3))_(2)overset(Delta)rarr2PbO+4NO_(2)+O2`
`Cu(NO_(3))_(2)(s)overset(Delta)rarrCuO(s)+2NO_(2)(g)+(1)/(2)O_(2)(g)`
or by action of concentrated nitric acid on metals like copper, silve, lead etc
`Cu+4NHO_(3)rarrCu(NO_(3))_(2)+2NO_(2)+2H_(2)O`
In the previous case the mixture of nitrogen dioxide and oxygen is passed through a U- table cooled by freezing mixture. `NO_(2)` condenses to a pale yellow liquid while oxygen escapes.
`NO_(2)` is produced on a large scale by oxidizing `NO` in the Ostwald process for the manufacture of nitric acid.
`NH_(4)NO_(3) overset(Delta)rarr N_(2)O+2H_(2)O`
`MNO_(3)rarrMNO_(2)+O_(2)`
`(M=Na, K" etc")`
`LiNO_(3)rarr Li_(2)O+NO_(2)+O_(2)`