Context: Pennsylvania (Pennsylvania German: "Pennsylvaani"), officially the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle. The commonwealth borders Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and the Canadian province of Ontario to the northwest, New York to the north, and New Jersey to the east., Philadelphia is the largest city in the Commonwealth of Pennsylvania and the fifth-most populous city in the United States, with an estimated population of 1,567,442 and more than 6 million in the seventh-largest metropolitan statistical area, . Philadelphia is the economic and cultural anchor of the Delaware Valleya region located in the Northeastern United States at the confluence of the Delaware and Schuylkill rivers with 7.2 million people residing in the eighth-largest combined statistical area in the United States., Cast iron is a group of iron-carbon alloys with a carbon content greater than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its colour when fractured: white cast iron has carbide impurities which allow cracks to pass straight through; grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks; ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing., The Chestnut Street Bridge is a bridge across the Schuylkill River that carries Chestnut Street in Philadelphia , USA . The original 1861 bridge was `` a bridge whose scale and use of cast iron made it singular in the United States and throughout the world '' . The 1957 bridge , now one way , helps connect West Philadelphia with the rest of the city ., Graphite, archaically referred to as plumbago, is a crystalline form of carbon, a semimetal, a native element mineral, and one of the allotropes of carbon. Graphite is the most stable form of carbon under standard conditions. Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds., The Eastern United States, commonly referred to as the American East or simply the East, is a region roughly coinciding with the boundaries of the United States established in the 1783 Treaty of Paris, which bounded the new country to the west along the Mississippi River. It is geographically diverse, spanning the Northeast and Southeast as well as the eastern part of the Central United States., The Delaware River is a major river on the Atlantic coast of the United States. Its watershed drains an area of in five U.S. statesNew York, New Jersey, Pennsylvania, Maryland and Delaware. Rising in two branches in New York state's Catskill Mountains, the river flows into Delaware Bay where its waters enter the Atlantic Ocean near Cape May in New Jersey and Cape Henlopen in Delaware. Not including Delaware Bay, the river's length including its two branches is .
The Delaware River is one of nineteen "Great Waters" recognized by the America's Great Waters Coalition., Tin is a chemical element with the symbol Sn (for ) and atomic number 50, is a post-transition metal in group 14 of the periodic table. It is obtained chiefly from the mineral cassiterite, which contains tin dioxide, SnO. Tin shows a chemical similarity to both of its neighbors in group 14, germanium and lead, and has two main oxidation states, +2 and the slightly more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table, thanks to its magic number of protons. It has two main allotropes: at room temperature, the stable allotrope is -tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey -tin, which has the diamond cubic structure. Metallic tin is not easily oxidized in air., A tributary or affluent is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage basin of its surface water and groundwater, leading the water out into an ocean., The Northeastern United States, also referred to as the American Northeast or simply the Northeast, is a geographical region of the United States of America bordered to the north by Canada, to the east by the Atlantic Ocean, to the south by the Southern United States, and to the west by the Midwestern United States. The Northeast is one of the four regions defined by the Census Bureau for the collection and analysis of statistics. The Census Bureau-defined region has a total area of with of that being land mass. Though lacking a unified cultural identity, the Northeastern region is the nation's most economically developed, densely populated, and culturally diverse region. Of the nation's four census regions, the Northeast is the second most urban, with 85 percent of its population residing in urban areas, led by the West with 90 percent., A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases a river flows into the ground and becomes dry at the end of its course without reaching another body of water. Small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. There are no official definitions for the generic term river as applied to geographic features, although in some countries or communities a stream is defined by its size. Many names for small rivers are specific to geographic location; examples are "run" in some parts of the United States, "burn" in Scotland and northeast England, and "beck" in northern England. Sometimes a river is defined as being larger than a creek, but not always: the language is vague., Iron is a chemical element with symbol Fe (from ) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars, where it is the last element to be produced with release of energy before the violent collapse of a supernova, which scatters the iron into space., The Pocono Mountains, commonly referred to as the Poconos, is a geographical, geological, and cultural region located in Northeastern Pennsylvania, United States. The Poconos are an upland of the larger Allegheny Plateau. Forming a escarpment overlooking the Delaware River and Delaware Water Gap to the east, the mountains are bordered on the north by Lake Wallenpaupack, on the west by the Wyoming Valley and the Coal Region, and to the south by the Lehigh Valley. It comes from the Munsee word "Pokawachne", which means "Creek Between Two Hills." Much of the Poconos region lies within the Greater New York-Newark, NY-NJ-CT-PA Combined Statistical Area. The wooded hills and valleys have long been a popular recreation area, accessible within a two-hour drive to millions of metropolitan area residents, with many communities having resort hotels with fishing, hunting, skiing, and other sports facilities., Southwest Philadelphia (formerly Kingsessing Township) is a section of Philadelphia, Pennsylvania, United States. The section can be described as extending from the western side of the Schuylkill River to the city line, with the SEPTA. The northern border is defined by the Philadelphia City Planning Commission as east from the city line along Baltimore Avenue moving south along 51st Street to Springfield Ave. It follows the train tracks until 49th Street. From 49th and Kingsessing Ave the line moves east along Kingsessing Ave. The line then moves south along 46th St to Paschall Ave where it jogs to join Grays Ferry where the line runs to the Schuylkill River., The Coal Region is a historically important coal-mining area in Northeastern Pennsylvania in the central Appalachian Mountains, comprising Lackawanna, Luzerne, Columbia, Carbon, Schuylkill, Northumberland, and the extreme northeast corner of Dauphin counties. Academics have made the distinction North Anthracite Coal Field and South Anthracite Coal Field (each of Pennsylvania), the lower region bearing the further classification Anthracite Uplands in physical geology., West Philadelphia, nicknamed West Philly, is a section of Philadelphia, Pennsylvania. Though there is no official definition of its boundaries, it is generally considered to reach from the western shore of the Schuylkill River, to City Avenue to the northwest, Cobbs Creek to the southwest, and the SEPTA Media/Elwyn Line to the south. An alternate definition includes all city land west of the Schuylkill; this would also include Southwest Philadelphia and its neighborhoods. The eastern side of West Philadelphia is also known as University City., Carbon (from "coal") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalentmaking four electrons available to form covalent chemical bonds. Three isotopes occur naturally, C and C being stable, while C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity., The Schuylkill River (, locally ) is an important river in central and eastern Pennsylvania. Two of its tributaries drain parts of the Pocono Mountains in the east and Coal Region in the center of the state. It flows for before joining the Delaware River as its largest tributary, in Philadelphia., Cobbs Creek is an tributary of Darby Creek in Delaware County, Pennsylvania, in the United States. It forms an approximate border between Montgomery County and Delaware County. After Cobbs Creek passes underneath Township Line Road (U.S. Route 1), it forms the border between Philadelphia County and Delaware County. It later joins Darby Creek before flowing into the Delaware River., The Delaware Valley is the valley through which the Delaware River flows. By extension, this toponym is commonly used to refer to the Philadelphia metropolitan area ("the [Lower] Delaware Valley Metropolitan Area"), which straddles the Lower Delaware River just north of its estuary., In chemistry, a carbide is a compound composed of carbon and a less electronegative element. Carbides can be generally classified by chemical bonding type as follows: (i) salt-like, (ii) covalent compounds, (iii) interstitial compounds, and (iv) "intermediate" transition metal carbides. Examples include calcium carbide (CaC), silicon carbide (SiC), tungsten carbide (WC) (often called simply "carbide" when referring to machine tooling), and cementite (FeC), each used in key industrial applications. The naming of ionic carbides is not systematic., The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates various forms of public transit servicesbus, subway and elevated rail, commuter rail, light rail and electric trolleybusthat serve 3.9 million people in five counties in and around Philadelphia, Pennsylvania, United States. SEPTA also manages construction projects that maintain, replace, and expand infrastructure and rolling stock., Subject: chestnut street bridge, Relation: located_in_the_administrative_territorial_entity, Options: (A) avenue (B) baltimore (C) basin (D) center (E) central (F) columbia (G) darby (H) dauphin (I) delaware (J) delaware county (K) earth (L) east (M) freshwater (N) gap (O) grays (P) jersey (Q) lead (R) mississippi (S) montgomery (T) montgomery county (U) most (V) newark (W) north (X) northumberland (Y) of (Z) ohio ([) pennsylvania (\) philadelphia (]) post (^) river (_) salt (`) southwest (a) street (b) the nation (c) the valley (d) united states of america (e) upland (f) west (g) wyoming (h) york
Output: pennsylvania