(a)
I_{2}+10 HNO_{3}$\overset{\mathrm{\Delta}}{\rightarrow}$2HIO_{3}+10NO_{2}+4H_{2}O
S+6 HNO_{3}$\overset{\mathrm{\Delta}}{\rightarrow}$ H_{2}SO_{4}+6NO_{2}+2H_{2}O
P_{4}+20 HNO_{3}$\overset{\mathrm{\Delta}}{\rightarrow}$4 H_{3}PO_{4}+20NO_{2}+4H_{2}O
C+4 HNO_{3}$\overset{\mathrm{\Delta}}{\rightarrow}$CO_{2}+4NO_{2}+2H_{2}O