Answer:1.28 x10^-4
Step-by-step explanation:
Convert 0.00634 grams C2H4Cl2 to moles by dividing grams by the molar mass.
0.00735g(1 mole C2H4Cl2/98.96g)= 6.406 x10^-5
Notice how grams cancel out leaving moles of C2H4Cl2.
Now multiply by the molar ratio of CL to C2H4Cl2,
(2 moles Cl/1 mole C2H4Cl2).
C2H4Cl2 cancels out, leaving moles of Cl.
2(6.406 x10^-5)= 1.28 x10^-4.
The equation as a whole....
0.00634g C2H4Cl2(1 MOLE C2H4Cl2) ( 2 moles Cl )
( 98.96 g ) (1 mole C2H4Cl2)=1.28 x10^-4