дано

m(C4H10) = 725 g

η(C4H8) = 8%

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Vпрак(C4H8)-?

C4H10-->C4H8+H2↑

M(C4H10) = 58g/mol

n(C4H10) = m/M = 725/58 = 12.5 mol

n(C4H10) = n(C4H8) = 12.5 mol

Vтеор(C4H8) = Vm*n(C4H8) = 22.4 * 12.5 = 280 L

Vпракт(C4H8) = Vтеор(C4H8)*η(C4H8) / 100% = 280*8%/100% = 22.4 L

ответ 22.4 л