Is it possible embed drupal civicrm Contribution Form code into page content?
Can any one please help me I was trying this for last 3 days, I can't find the solution.
Yes, you can install the Webform-CiviCRM module, and this allows you to embed contribution fields in a webform (which is a drupal content type).
Short answer: no, not in generic page content, unless you use an iframe.
Coleman's solution above relies on a lot of complex code (that he wrote ...) to do the embedding/integration for you, and is the best solution if you have Drupal and want to use a Drupal-native form for the contribution page. The other option is to use Drupal commerce and rely on more complex and less reliable integration.
A donation form is not as simple as a regular form, it relies on a lot of server work and magic (for a start, for security, but also for input error handling for example), so simply creating a form that posts to a CiviCRM url won't work.