Is it possible to apply theme to a Master page?

Answer:

With reference to the following link:
http://msdn.microsoft.com/en-us/library/wtxbf3hh.aspx

If we add the theme attribute to the @ Master directive, the page will raise an error when it runs.

But we can apply themes by using the following approaches:-

1. As master pages is placeholder/templated and it is merged with the content page very early in the page execution life-cycle. The theme that is applied to the the content pageis applied to the master page as well.

2. If the site as a whole is configured to use a theme by including a theme definition in the pages element.

Hence there is no theme attribute in the @Master directive.