题干

浓硝酸、稀硝酸都具有强氧化性,某学习小组探究浓、稀硝酸氧化性的相对强弱,按下图装置进行试验(夹持仪器的装置已略去).实验表明浓硝酸能将NO氧化成NO2,而稀硝酸不能氧化NO.由此得出的结论是浓硝酸的氧化性强于稀硝酸.

可选药品:浓硝酸、3mo/L稀硝酸、蒸馏水、浓硫酸、氢氧化钠溶液及二氧化碳

已知:氢氧化钠溶液不与NO反应,能与NO2反应

2NO2+2NaOH═NaNO3+NaNO2+H2O

上一题 下一题 0.0难度 选择题 更新时间:2019-12-30 06:16:08

答案(点此获取答案解析)

同类题4

根据短文理解,选择正确答案。

    I returned home the other night, tired. My husband asked me how my evening was, “Great.” I told him. I had spent 90 minutes in a gym with 10 Ping-Pong tables and all kinds of players, all playing a little ball over the net. By 9 pm, I was excited, tired, satisfied. I had beaten two young men half my age and lost battles against other competitors. To an observer, the night was common. To me, it was a lucky thing that I hadn't expected.

    I had taken up Ping-Pong during college, and in my 30s took more advanced lessons. However, a serious accident hurt my leg, which made me unable to take exercise. Months later, I tried to play Ping-Pong but my leg pained for a week. I put the game out of my mind.

    When I was 53, one day my bad leg was working a little bit better. Could Ping-Pong be possible for me, now---in my condition, at my age? I tried to play Ping-Pong again

    Ping-Pong is a sport which requires endurance(耐力). Players need quick foot work and upper body movements to return balls, requiring faster response time than tennis.

    Playing Ping-Pong offers benefits for the brain. A study of 164 women aged 60 and older showed that Ping-Pong improved cognitive(认知)function more than dancing, walking or gymnastics. “The great thing about our sport is that it can be played by anyone,” said Jimmy Butler, a four-time national USA Table Tennis Association winner. “I see 90-year-olds and 10-year-olds.”

    Years passed and my endurance improved. People started to praise my shots. I won a game. Then I won agin. These days, I feel wonderful, I believe this sport is the fountain (源泉)of youth.