Explanations:Proper nouns are specific names of people, places, or things. They are always capitalized in English, regardless of their position in a sentence. In the context of geography, proper nouns include the names of states, rivers, cities, and other geographical features. For example, "West Bengal" is a proper noun because it is the specific name of a state in India.
Common nouns, on the other hand, refer to general categories of things. For instance, "river" is a common noun because it can refer to any river, not a specific one. Similarly, "state" is a common noun because it refers to any administrative division, not a specific one like "West Bengal."
Prepositions are words that show the relationship between a noun or pronoun and other parts of the sentence. Examples of prepositions include "through," "in," "on," "at," and "by." These words are not capitalized unless they are the first word in a sentence or part of a title.
In the given sentence, "The river runs through the state of West Bengal," the word "West Bengal" is the only proper noun. It is the specific name of a state in India and is capitalized accordingly. The other words in the sentence, such as "river," "state," and "through," are not proper nouns. "River" and "state" are common nouns, and "through" is a preposition.
Understanding the difference between proper nouns and other types of words is crucial for correct grammar and effective communication. Proper nouns are essential for identifying specific entities, while common nouns and prepositions help to describe and relate these entities within a sentence.