Answer
a. $NO_2$
b. $CH_2$
c. $P_2O_5$
d. $COH_2$
Work Step by Step
a. $N_2O_4\Rightarrow NO_2$
Common factor of 2
b. $C_3H_6\Rightarrow CH_2$
Common factor of 3
c. $P_4O_{10}\Rightarrow P_2O_5$
Common factor of 2
d. $C_6O_6H_{12}\Rightarrow CHO_2$
Common factor of 6
