题干

下列除去少量杂质的方法正确的是(   )

A:Zn粉中含少量的ZnO:加入足量稀H2SO4充分反应后过滤

B:Zn(NO32溶液中含少量AgNO3:加入过量Zn粉充分反应后过滤

C:Na2SO4溶液中含少量H2SO4:加入适量Ba(OH)2溶液充分反应后过滤

D:CaCO3 固体中含少量 Na2CO3:加入足量水溶解、过滤、滤液蒸发结晶

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答案(点此获取答案解析)

B

同类题2

Group exercise is one of the most effective ways to improve physical fitness and sustain a healthy lifestyle.Group exercise is challenging, yet fun and empowering! Of course everyone knows that exercise is good for the body.However, studies have shown that when exercise is performed in groups, it's not only great for improving physical health but for psychological health. It's an opportunity to be social, release endorphins, and improve your strength. Additionally, group exercise creates a community feel and the shared common goal motivates participants to work hard. The instrumental support of taking on a fitness journey with others proves more effective than going to the gym alone.
        Another beneficial aspect of group exercise is the informational support participants receive from the instructor. Many people fear the gym because they feel lost and don't want to embarrass themselves. If you feel you can relate, then group training is an even better option for you. It's a great opportunity to learn more about fitness through the clear instruction and supervision of a fitness instructor. If you're tired of wandering around the gym wasting time and becoming bored, you can attend an upbeat group fitness class that'll keep your workout on track. Don't let fitness frighten you!
        If you're serious about wanting to live a healthy lifestyle, it's extremely important to surround yourself with people who'll provide you with the proper emotional support. I wouldn't scold anyone for deciding to party on weekends and in turn I wouldn't expect anyone to give offence to me for focusing on my health. Surround yourself with people who uplift, encourage and understand you! Make fitness even more fun by trying something new or any group fitness class, with a friend. Plan to go for a jog together. Then try a fun healthy restaurant or fresh juice bar! Fitness can be both fun and social!
        Surrounding yourself with people who'll provide you with respect support can be very beneficial while working towards reaching health and fitness goals. First, decide to do it for yourself and work towards staying positive. Then make sure the people you surround yourself with are supportive. Don't let negativity ruin your motivation.