题目

NA表示阿佛加德罗常数，下列说法正确的是( )A.36 g H2O的物质的量为1 molB.常温常压下，1mol Cl2的体积是22.4 LC.0.5mol·L-1NaCl溶液中含有0.5mol Na+D.1molCO2中含有的分子数约为NA 答案：【答案】D【解析】A．36g水的物质的量=2mol，A错误；B．标准状况下，1mol Cl2的体积是22.4 L，B错误；C．题干中没有给出溶液的体积，不能根据n=cV计算出含有的Na+的物质的量，C错误；D．1molCO2中含有的分子数N=nNA，因此1molCO2中含有的分子数约为NA，D正确；故选D。Computers can help many workers. They can also help thieves. There was one thief who worked in a bank of the United States. He paid for everything he needed by check (支票). Then he told the computer not to take any money from his account for the checks he wrote. The bank’s computer did what he said. And it did not take any money from his bank account. One day the computer broke down. People had to do the computer’s work. They soon found out what was happening. Another thief, who worked for a bank saw people filling in deposit forms (存款单). Many of these people did not know their account numbers, so they wrote only their names on the forms. They left empty places for their account numbers. The thief wrote his own account number in this place. When the computer read these forms it looked only at the account numbers. It did not look at the customers’ names. It paid the money on these deposit forms into the thief’s account .                            Then there was the bank worker who told the bank computer to take ten cents off every customer’s account each month and put it into his own account. For a long time the bank’s customers did not notice that they were losing ten cents every month. But then someone did notice and told the bank. That was the end of that little game! 1.What was the first thief? A．A computer engineer.                    B．A customer.        C．A bank worker.  D．We don’t know. 2.How did the first thief steal money from the bank? A．He broke the computer down and stole money from it. B．He paid for everything by check instead of cash. C．He took money away from the bank. D．He told the computer not to take away money from his account. 3.How many kinds of crimes in a bank are mentioned? A．Two.             B．Three.            C．Four.             D．Five. 4.What can we infer from the passage? A．None of the thieves has been caught by the police up to now. B．A lot of money is missing from the bank of the United States each year. C．The computers in the bank will be changed to prevent money from being stolen. D．There will be no crimes in the bank any more since so many crimes have been found out.