4. For the species O2, , and , use the molecular orbital model to give the electron configuration and the bond order for each. Which has the strongest bond? (10%)

2. The reaction of ethane gas (C2H6) with chlorine gas produces C2H5Cl as its main product (along with HCl) and a variety of other minor products. Calculate the percent yield of C2H5Cl if the reaction of 300. g of ethane with 650. g of chlorine produced 490. g of C2H5Cl. (atomic mass: C, 12.01； Cl, 35.45； H, 1.008) (8%)