【单选题】
既能使石蕊试液变红,又能使品红试液变为无色,还能使溴水褪色的是()。
①
<img class="kfformula" src="20200629/1593437261129283.png" data-latex="{SO}_{2}" width="50" height="33"/>
②
<img class="kfformula" src="20200629/1593437261775483.png" data-latex="{H}_{2}S" width="48" height="31"/>
③
<img class="kfformula" src="20200629/1593437261194518.png" data-latex="{C1}_{2}" width="47" height="34"/>
④
<img class="kfformula" src="20200629/1593437261658410.png" data-latex="CO" width="39" height="32"/>