Suppose that you needed to make a pen for some small animals. you have 12 m of fencing. you decide to make a circular pen, because if you wish to enclose an area using a given length of fencing, then a circular fence encloses a larger area than a fence of any other shape. what is the radius r of the pen? express your answer in meters to four significant figures.

Alice and marge are studying the properties of matter. the girls placed some an iron nail in a beaker containing water. iron is a solid metal at room temperature. iron is a shiny and malleable; it can be formed into shapes like the nails the girls used. iron will turn reddish-brown in the presence of air or water as it rusts. iron is a good conductor of electricity and heat. after 48 hours, the girls checked the nail in the water and compared it to the nail they left on the lab bench. here is a photo of their results. based on the girls' experiment, what is a chemical property of iron? a) iron is malleable. b) iron rusts in water. c) iron is a strong metal. d) iron is a good conductor.