6. Approximately how many grams of water are produced from the complete reaction of 115 g of butane?*
2C4 H10 + 1302 → 8CO2 + 10H2O
O 369
O 178 g
O 357 g
O 7149

Copper, silver, aluminum, cobalt, chromium, mercury 

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

The total number of electrons is 14