What Form is it, even when it is null?

Is this possible in some way?  Can I tell that this variable is the Preferences form in this variable while it is still null?

 Preferences dontknowwhatitis = null;

            if (dontknowwhatitis is Preferences)
            {
                MessageBox.Show("is there any way to tell that it is the Preferences form before creating it?");
            }