Question

WHY DO WE SAY "THE UNITED STATES OF AMARICA" BUT NOT "THE INDIA"

Answer 1

When you are addressing a country on the basis of its full name that's when you use 'the'.For example you should not say 'the China' instead you must just say China, on the other hand if you are addressing China by its full name you have to state it as 'the People's Republic of China'.

The same goes for the US and UK as the United States of America and United Kingdom are the full names of America and Britain respectively. Henceforth while addressing India by its full name we address it as the Republic of India

RULE OF THUMB :Only use the as a prefix 'the' for a country while stating it's full name​​​.

Although 'The' might be missing from the full name in the documents of the respective law enforceable file or paper you still have to pronounce it with the 'the' .​​​

You can use the for almost all the countries in the world when you are stating it's full name

Exception 1:The Vatican City The Vatican City is smallest country in the world and seeing how it's full name is it's general name it can be addressed as the Vatican City or the Holy See.

Exception 2: It is not valid to use 'the' if the country doesn't have a enforceable constitution.

Exception 3: Former Soviet satellite states. Countries such as Ukraine and Georgia believe there countries name reflects there constitution and governance hence they don't have a full name, meaning there general name is there full name, therefore using the would be invalid although they have an an enforceable constitution.

Thereby,  if you want to use the to address India state it as the Republic of India.

Answer 2

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Here's your answer

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$<b>In case of United States of america'The' is used because it refers to some states of America,means not single and while in case of India, It refers to only one independent body, India. There are 50 States in United States of America,and by the name it is saying about the word state so we use the but not the same in case of India. </b>$

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Hope it helps you