题干

铜片与浓硝酸可以发生如下反应:Cu+4HNO3=Cu(NO3)2+2X↑+2H2O对该反应的下列说法中正确的是(   )

A:生成物X的化学式为H2

B:反应中N元素化合价改变的原子与N元素化合价不变的原子的个数比为1:1

C:浓硝酸属于纯净物

D:反应物Cu与生成物H2O的质量比为32:9

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B

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    After a homeless man offered a college student in England all the money he had so she'd be able to get home safely, the woman is paying it forward—in a massive way.

    The story began in early December. It was about 3 a.m. and Harrison-Bentzen was panic. “I came out after a student night out and realized I didn't have any battery on my phone. I'd lost my friends,” the 22-year-old told BBC Radio 5. She'd also lost her bank card, she discovered, and she had no money.

    Just then, a homeless man, known only as Robbie, approached the young woman and asked her if she needed help. He reached into his pocket and pulled out all the money he had—loose change amounting to about $4.60. He insisted that Harrison-Bentzen take it to pay for a taxi so she'd get home safely.

    Harrison-Bentzen, a student at the University of Central Lancashire in Preston, England, says she refused to take Robbie's money and found another way to get home. But following her encounter(偶然相遇)with the generous man, she says she couldn't get him out of her mind.

    For the next few days, the student searched for Robbie, driving around the streets with her mom and using social media in an attempt to locate the man. In that time, Harrison-Bentzen says she learned more about Robbie and discovered that he actually had a reputation for helping strangers.

    Finally, after four days of driving around Preston, Harrison-Bentzen found Robbie. She was determined to do something to help change Robbie's life.

    So, earlier this month, the student launched a fundraising campaign in Robbie's name. She explained that she would be spending 24 hours on the streets, so as to “understand the difficulties” that the homeless face on a daily basis.

    Harrison-Bentzen says she had initially(最初)hoped to raise about $780 with her campaign. Her expectations, however, were quickly blown out of the water. As of Thursday morning, 4,800 people have donated almost $50,000.