Does SharePoint 2010 solution work on SharePoint 2013?

Answer : The solution gets deployed to the 14 hive, because of a setting in the manifest.xml file in the page. If you open up the package in Visual Studio, or you can open the manifest file directly to change this.
If you created your solution in SharePoint 2010 the <Solution> element in the manifest file will have a property that says "SharePointProductVersion="14.0". If you change this to 15.0 the solution should deploy to the 15 hive.