When no results are returned, you have an 'empty' list. This is same as a new list created.
For it, you can try any of the following:
if (!returnedResult.Any())
{
}
if(returnedResult.Count() > 0)
{
}
var returnedResult = (from Q in myDataContext select Q.ID).ToList();
if (returnedResult.Count > 0)
{
}