将<img class="kfformula" src="20200623/1592893099409428.png" data-latex="{Fe(OH)}_{2}" width="101" height="24"/>露置在空气中加热灼烧所得的产物为()。
①
<img class="kfformula" src="20200623/1592893099585801.png" data-latex="{Fe}_{2}{O}_{3}" width="81" height="32"/>
②
<img class="kfformula" src="20200623/1592893099561989.png" data-latex="F{e}_{2}{O}_{3}" width="88" height="36"/>
④
<img class="kfformula" src="20200623/1592893099960836.png" data-latex="{Fe(OH)}_{3}" width="96" height="32"/>