In PDF I have 3 spaces in between the word but while exporting that pdf to word that 3 spaces converted to single space anyone faced this issue. How to i retain word file as per pdf without missing 3 spaces.

You were already given the correct answer above:

         Acrobat doesn't know it's three spaces. It isn't actually spaces, just a gap. Probably nothing you can do.

          &

          If the file is not tagged Acrobat has to guess and may guess wrong. No work around.

The fact is that PDF is not a source document file format, but rather, a final form file format. What you see in Word, for example has the full context of characters in words in sentences in paragraphs in articles, etc. What PDF has is simply runs of text of 1 or more characters at a particular location in a particular font and style with a particular rotation and size. Sometimes, these runs of text include space characters and sometimes, especially when text is justified, not! In the latter case, space characters are replaced by advancing to a new location instead of explicit use of space characters.

Word=>PDF=>Word is not an identity operation and due to the nature of PDF lacking context, the differences you see may be large or small.

When PDF is tagged (an option when creating the PDF file from Office, for example), an attempt is made to put context of the original content into the PDF file, but lacking such tagging information, Acrobat has to guess what the spacing from one text run to another really consists of in terms of space characters from the empty spaces.

Bottom line, try tagging when creating the PDF and see if that makes a difference when exporting PDF back to Word.

          - Dov