Neoprene is the polymer of 2-chlorobuta-1,3-diene, CH2=C(Cl)-CH=CH2, formed by 1,4-addition. Taking C = 12, H = 1, Cl = 35.5, the mass percent of chlorine in neoprene is

JEE Advanced levelSingle correct optionDifficulty 3 of 3pl036

Neoprene is the polymer of 2-chlorobuta-1,3-diene, $CH X_{2} = C (Cl) - CH = CH X_{2}$ , formed by 1,4-addition. Taking C = 12, H = 1, Cl = 35.5, the mass percent of chlorine in neoprene is

The repeat unit is

- [CH X_{2} - C (Cl) = CH - CH X_{2}] X^{-}

C X_{4} H X_{5} Cl

with mass

48 + 5 + 35.5 = 88.5

. Chlorine is

35.5/88.5 \times 100 = 40.1

percent. Using the vinyl chloride unit (

C X_{2} H X_{3} Cl

) would give 56.8 percent.