题目

漂白液的主要成分是NaClO，NaClO中氯元素的化合价是（ ） A．﹣1  B．0    C．+1   D．+5 答案：【考点】D6：有关元素化合价的计算． 【分析】根据在化合物中正负化合价代数和为零，结合次氯酸钠的化学式进行解答本题． 【解答】解：钠元素显+1价，氧元素显﹣2价，设氯元素的化合价是x，根据在化合物中正负化合价代数和为零，可得：（+1）+x+（﹣2）=0，则x=+1价． 故选C．We had just covered a distance of three miles        the engine         and the car came to a stopA．then; was brokenB．when; broke downC．until; was failedD．since; burst out