A Buna-S chain has three butadiene units (C4H6, 54 g/mol each in the chain) for every one styrene unit (C8H8, 104 g/mol in the chain). Neglecting end groups, the mass percent of styrene in the copolymer is closest to

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JEE Advanced levelSingle correct optionDifficulty 3 of 3pl090

A Buna-S chain has three butadiene units ( $C X_{4} H X_{6}$ , 54 g/mol each in the chain) for every one styrene unit ( $C X_{8} H X_{8}$ , 104 g/mol in the chain). Neglecting end groups, the mass percent of styrene in the copolymer is closest to

A25.0
B39.1
C33.3
D19.4

Answer: B

Mass of three butadiene units = 162 and one styrene unit = 104, total 266. Styrene percent = 104/266 x 100 = 39.1 percent. 25.0 is the mole fraction of styrene, which is not what was asked.

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A Buna-S chain has three butadiene units (CX4​HX6​, 54 g/mol each in the chain) for every one styrene unit (CX8​HX8​, 104 g/mol in the chain). Neglecting end groups, the mass percent of styrene in the copolymer is closest to

Answer: B

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A Buna-S chain has three butadiene units ( $C X_{4} H X_{6}$ , 54 g/mol each in the chain) for every one styrene unit ( $C X_{8} H X_{8}$ , 104 g/mol in the chain). Neglecting end groups, the mass percent of styrene in the copolymer is closest to