What is 125000 in scientific notation?

Why does his teacher ask him to balance the equation by including the correct coefficient

Which of the following represents the ester functional group? a. -coo- b. -cho c. -cooh d. c=o

How many moles of lead are in 1.50 x 10^12 atoms of lead? could you explain the answer as well and not just give it to me i am refreshing for finals and i need to know how to do it