Butane, starred at the 2 position, as an example of an achiral carbon.
<a href="//commons.wikimedia.org/wiki/User:NEUROtiker" title="User:NEUROtiker">NEUROtiker</a> <sup><a href="//commons.wikimedia.org/wiki/User_talk:NEUROtiker" title="User talk:NEUROtiker">⇌</a></sup>, <a href="//commons.wikimedia.org/wiki/User:GKFX" title="User:GKFX">GKFX</a><sup><a href="//commons.wikimedia.org/wiki/User_talk:GKFX" title="User talk:GKFX">talk</a></sup>
Based on <a href="//commons.wikimedia.org/wiki/File:Butan_Skelett.svg" title="File:Butan Skelett.svg">File:Butan Skelett.svg</a>. Edited by me (<a href="//commons.wikimedia.org/wiki/User:GKFX" title="User:GKFX">GKFX</a><sup><a href="//commons.wikimedia.org/wiki/User_talk:GKFX" title="User talk:GKFX">talk</a></sup>) to add asterisk.