A 170 g ball is tied to a string. It is pulled to an angle of 4.40° and released to swing as a pendulum. A student with a stopwatch finds that 12 oscillations take 9.00 s. How long is the string? Express your answer in centimeters (cm).

Iron is a transition metal with multiple oxidation numbers. (answer the following) a. what is the iron (ii) ion? how does it differ from the iron (iii) ion? b. if iron were to bond with oxygen, predict the formula for each oxidation number of iron. c. how would each formula be named?