Addition Polymerization Involves Double Bond Cleavage

Steps:

• Define addition polymerization as the linking of monomers with unsaturated bonds, like alkenes, without eliminating small molecules.
• Identify the key chemical change: the pi bond in C=C breaks to allow monomers to join via new C-C sigma bonds.
• Confirm no by-products form, distinguishing it from condensation polymerization.
• Match this to option A, which describes breaking C=C and forming C-C bonds.

Why A is correct:

• Addition polymers, such as polyethene, form when the double bond in monomers like ethene opens, creating a saturated chain per the reaction n CH₂=CH₂ → [-CH₂-CH₂-]ₙ.

Why the others are wrong:

• B describes ester bond formation, typical of condensation polymers like polyesters.
• C involves water elimination, a hallmark of condensation polymerization, not addition.
• D refers to ring opening, which applies to specific polymers like nylon but not general addition types.

Final answer: A