A string has a mass of 0.8Kg. The length of the string is 2m. The tension in the string is 5N. The string is stretched and fixed at both ends such that when struck it forms the second harmonic. Calculate the frequency of the wave which results on the string.

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?