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欲使100g 5%的硝酸钠溶液浓度增大到20%,需再加入硝酸钠固体( )
A. 18.75g
B. 19.75g
C. 20g
D. 25g
人气:191 ℃ 时间:2020-01-27 09:00:31
解答
100g 5%的硝酸钠溶液浓度增大到20%,设再加入硝酸钠固体的质量为x,则(100g+x)×20%=100g×5%+x,x=18.75g.
故选:A.
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