The mass only image is not as necessary now that it is included in a combined image with molar concentration that recently got featured status (below):
Delist per nom, obviously. Superseded in articles by new one. --jjron (talk) 05:43, 7 October 2009 (UTC)[reply]
Delist This picture has been replaced by the combined version. There's no reason to have them both featured. Makeemlighter (talk) 02:37, 10 October 2009 (UTC)[reply]