avem reactiile
a moli a a 3a
C11H24 ----> C7H8 + C4H10 + 3H2
1 1 1 3
b moli b
C11H24 ---> C11H24 netransformat
1 1
=> amestecul de gaze este
a+a+3a+b = 5a+b moli amestec de gaze
fractia.H2 = 0,75fractia.C11H24.netransformat
fractia.H2 = 3a/5a+b
fractia.C11H24.netransf. = b/5a+b
=> 3a/5a+b = 0,75b/5a+b
=> 3a = 0,75b => 4a = b
%C11H24.descompus = ax100/a+b = 100a/5a = 20%