人尿中含氮的質(zhì)量分?jǐn)?shù)(質(zhì)量百分含量)為0.93%,如果這些氮都存在于尿素中,則人尿中含尿素的質(zhì)量分?jǐn)?shù)(質(zhì)量百分含量)約為( ?。?br/>A. 1%
B. 2%
C. 3%
D. 4%
假設(shè)人尿的質(zhì)量為100g,則100g人尿中氮元素的質(zhì)量=100g×0.93%=0.93g
則100g人尿中含尿素的質(zhì)量=
×100%=1.993g
人尿中含尿素[CO(NH
2)
2]的質(zhì)量分?jǐn)?shù)=
×100%=1.993%≈2%
故選B.