Case :-

Case is the study of placement of noun in a sentence for different purpose.

Kind of case

There are four kinds of case
(1) Nominative case
(2) Objective case
(3) Possessive case
(4) Vocative case

(1) Nominative case:- Noun or pronoun which is used as subject is known as nominative case.
Ex- Ram is playing there.
In this sentence Ram is nominative.

(2) Objective case :- Noun or pronoun which is used as object is known as objective case.
Ex- I have called Ram
In this sentence Ram is objective.

(3) Possessive case :- Noun or pronoun which is used to so relation is known as possessive case.
Ex- This is Ram's house.

(4) Vocative case :- Noun or pronoun which is used to address anyone.
Ex- Ram, where are you going?

Some Important Rule

Nominative Case Generally a noun nominative case comes before verb but in the following sentences it comes after verb.

(1). In an interrogative sentence
Ex- Where you are going. ( Incorrect )
Ex- Where are you going. ( Correct )

(2). In an Optative sentence
Ex- I may come in sir. ( Incorrect )
Ex- May i come in sir! ( Correct )

(3). In it, there, here sentences
Ex- There a book is on the table. ( Incorrect )
Ex- There is a book on the table. ( Correct )

(4). In possessive pronoun sentences
Ex- Mine a good pen is on the table. ( Incorrect )
Ex- Mine is a good pen on the table. ( Correct )

(5). In hardly, scarcely, no sooner sentences
Ex- Hardly i had reached there when he come. ( Incorrect )
Ex- Hardly had i reached there when he come.( Correct )

Possessive case :- How to change a noun into possessive case

(1). Living nouns - by 's
Ex- This is the house of Ram. ( Incorrect )
Ex- This is Ram's house. ( Correct )

(2). Non-living nouns - by 'of'
Ex- This is table's leg. ( Incorrect )
Ex- This is the leg of table. ( Correct )

Exception:-

(1). A noun indicating time - also by 's
Ex- I need a day's leave.

(2). A noun indicating place - also by 's
Ex- These are Delhi's roads.

(3). In a non-living noun works as living - also by 's
Ex- He was killed by gun's bullet.

(4). Units - also by 's
Ex- He wants a ton's coal.

(5). A compound noun - by 's with the last part
Ex- This is my father-in-law's house.

(6). 's' sound or 's' itself at last - always
Ex- This is girls' common room.

(7). Two persons same time owner - by 's with last
Ex- This is Ram and Mohan's house.

(8). Two person separate owners - by 's with both
Ex- There are Ram's and Mohan's houses.

(9). Double relation - always by 'of '
Ex- This is mohan's friend's pen. ( Incorrect )
This is the pen of mohan's friend.