自然界中的硫化氢常含于火山喷发气和温泉中，硫化氢是由氢元素和氧元素组成．
（1）硫化氢中硫元素的化合价为-2价，则硫化氢的化学式为______
（2）硫化氢气体在空气中燃烧的产物是SO2和X，已知X是一种氧化物，则X的化学式为______，SO2中硫元素的化合价为______．
（1）硫化氢中硫元素的化合价为-2价，氢元素显+1价，其化学式为：H2S．
（2）硫化氢气体在空气中燃烧的产物是SO2和X，已知X是一种氧化物，由质量守恒定律，反应前后元素种类不变，X为氢元素形成的氧化物，X的化学式为H2O．
氧元素显-2价，设硫元素的化合价是x，根据在化合物中正负化合价代数和为零，可得：x+（-2）×20，则x=+4．
故答案为：（1）H2S；（2）H2O；+4．
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| Do you often think of your parents? You may say, "Of course, I __1__. I often buy presents __2__ my mother and my father on some important days." Here's a story about my friend. She works in a big city. She is very busy. So she doesn't have time __3__ her parents. But she often calls her parents. Every time, she dials (拨) the number, but then she puts down the telephone. __4__five minutes, she dials the number again. Later, I ask, "Why do you dial the number __5__ ?" She smiles, "My parents are __6__ and slow. They can't get to the telephone quickly. I always do so when I call them. I only want to give them __7__ to answer the telephone. My friend is a good girl. She is always __8__ of her parents. You also want to be a __9__ child, right? Please always remember (记住) to __10__ your parents in every situation (在各种情况), not just on some important days. | ||||
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