Column(I) (Oxide of nitrogen)	Column(II) (Colour)
(p) NO	(i) Colourless solid
(q) NO2	(ii) Colourless solid
(r) N2O3	(iii) Brown gas
(s) N2O5	(iv) Colourless gas

(p)$\to$(iv); (q)$\to$(iii); (r)$\to$(ii); (s)$\to$(i)

(p)$\to$(i); (q)$\to$(iii); (r)$\to$(ii); (s)$\to$(iv)

(p)$\to$(i); (q)$\to$(ii); (r)$\to$(iii); (s)$\to$(iv)

(p)$\to$(iv); (q)$\to$(ii); (r)$\to$(iii); (s)$\to$(i)