I had written an article over Highly searched keywords some days ago. When i search it in google using top searched keywords article-stack, it returns many results from my site. But none of them was really pointing to actual article.
Is there anything wrong with sitemap.xml of my site or with google search?
Its possible there is something wrong with your sitemap - JohnC outlines how to check this, its theoretically possible that there is something wrong with google search, but highly unlikely.
If by "some days" ago you mean you published your article fairly recently, say, 1-2 weeks ago then its most likely that google hasn't indexed the article yet.
