Question

ram runs round the tree.......... here round is which parts of speech

Answer 1

Common nouns can be preceded by determiners: a, the, some, a few, my, ...

If a word is a common noun, then the following sentence makes sense when the word is inserted:

My [insert noun] (is/are here).

For instance, house is a noun, so:

My house is here, 

makes sense. 

The word happy, however, isn't a noun, so:

My happy is here,

does not make sense.

Note on Using the Tests

Most tests show whether a word could be a noun - sometimes. They do notindicate the word is a noun in the given sentence. For instance, 

The delicate and time-consuming work is important.

Using our test:

My work is here.

makes sense. So work can be a noun. If we remember that Theis a determiner, then we see work is preceded by a determiner (and some adjectives) so work is clearly a noun in our sentence. If we do not remember this, then we can apply our test with my in the sentence:

My delicate and time-consuming work is important.

Showing that work is a noun in the given sentence. 

In this sentence:

They work till they drop.

We cannot precede the word work with my in:

My work till they drop. 

Therefore work isn't a noun in this sentence.

Examples of Nouns and Non-Nouns

Here are some examples of applying the test on nouns and non-nouns:
NounsNon-N

Answer 2

here , the parts of speech of "round" is 'preposition'.