若弱酸的PKa = 4.750,则 Ka 的值为<br/> A、1.8<img src="https://static.zxtiku.com/wangke/imgs/topic/b0702c66f6209f5f1ef83de05589293c.jpg"/><img src="https://static.zxtiku.com/wangke/imgs/topic/4e1e50325f00e13595ad5c41c6d62245.jpg"/><br/> B、1.800<img src="https://static.zxtiku.com/wangke/imgs/topic/b0702c66f6209f5f1ef83de05589293c.jpg"/><img src="https://static.zxtiku.com/wangke/imgs/topic/4e1e50325f00e13595ad5c41c6d62245.jpg"/><br/> C、1.80<img src="https://static.zxtiku.com/wangke/imgs/topic/b0702c66f6209f5f1ef83de05589293c.jpg"/><img src="https://static.zxtiku.com/wangke/imgs/topic/4e1e50325f00e13595ad5c41c6d62245.jpg"/><br/> D、1.8000<img src="https://static.zxtiku.com/wangke/imgs/topic/b0702c66f6209f5f1ef83de05589293c.jpg"/><img src="https://static.zxtiku.com/wangke/imgs/topic/4e1e50325f00e13595ad5c41c6d62245.jpg"/>