Superscript / Subscript in Cloze (Embedded question type)

Use the insert special character icon in the editor (the Omega Symbol). If it's not there google for the unicode HTML notation

Limited list of HTML Unicode character sets -http://www.fileformat.info/info/unicode/block/superscripts_and_subscripts/list.htm

Find what you need from the list in the URL above, click the link and copy and paste into the editor and it will display when previewed.