Mass of Cyclohexen : 10.2 g
Further explanation
Reaction
3 C6H10 + 4 Na2Cr2O7 + 16 H2SO4 >
3 C6H10O4 + 4 Cr2(SO4)3 + 4Na2SO4 + 16 H2O
mol C6H10 : mol C6H10O4 = 3 : 3 = 1 : 1
![\tt \%yield=(actual)/(theoretical)* 100\%\\\\68.6\%=(12.5)/(theoretical)* 100\%\\\\theoretical=18.22~g](https://img.qammunity.org/2021/formulas/chemistry/college/fuog8aez2der0xdy7ti7t323grkspe7vcn.png)
12.5 grams of C6H10O4 , mol C6H10O4 (MW 146.14 g/mol):
![\tt (18.22)/(148)=0.123](https://img.qammunity.org/2021/formulas/chemistry/college/nzbg36st7ombvr4ercwin84hkl0phnh3x3.png)
mol C6H10 = mol C6H10O4 = 0.124
mass C6H10 :
![\tt 0.124* 82.16=10.2~g](https://img.qammunity.org/2021/formulas/chemistry/college/5n4iuha9e9mmfgfkcfr1zgz9kd9725cikj.png)