A linear silicone is to be made by hydrolysis and condensation of a mixture of (CH3)2SiCl2 and (CH3)3SiCl so that every chain has, on average, 50 (CH3)2SiO units and two (CH3)3Si end groups. The required mole ratio (CH3)2SiCl2:(CH3)3SiCl is

JEE Advanced levelSingle correct optionDifficulty 3 of 3pb092

A linear silicone is to be made by hydrolysis and condensation of a mixture of $(CH X_{3}) X_{2} SiCl X_{2}$ and $(CH X_{3}) X_{3} SiCl$ so that every chain has, on average, 50 $(CH X_{3}) X_{2} SiO$ units and two $(CH X_{3}) X_{3} Si$ end groups. The required mole ratio $(CH X_{3}) X_{2} SiCl X_{2} : (CH X_{3}) X_{3} SiCl$ is

Each chain needs two end-capping

(CH X_{3}) X_{3} SiCl

molecules and 50

(CH X_{3}) X_{2} SiCl X_{2}

molecules. The ratio is

50 : 2 = 25 : 1