The correct answer is A. I and II only.
Step-by-step explanation:
Addition polymers are formed through a process called addition polymerization, in which monomers join together without the elimination of any byproducts. The given options include three compounds:
I. H2C=CH(CH3) (1-butene)
II. H2C=CH2 (ethylene)
III. H2C=CHCl (vinyl chloride)
To form an addition polymer, the monomers need to have a carbon-carbon double bond (C=C). This double bond allows for the bonding of multiple monomers to create a long chain polymer.
Option I (1-butene) has a carbon-carbon double bond and can undergo addition polymerization.
Option II (ethylene) also has a carbon-carbon double bond and can undergo addition polymerization.
Option III (vinyl chloride) has a carbon-chlorine bond instead of a carbon-carbon double bond. This type of bond does not allow for the formation of an addition polymer.
Therefore, only options I and II (H2C=CH(CH3) and H2C=CH2) can react to form addition polymers. The correct answer is A. I and II only.