Question

18．溶質(zhì)質(zhì)量分?jǐn)?shù)為1%的食鹽水是指（　�。�

• A． 100g水中溶有1g食鹽
• B． 99g水中溶有1g食鹽
• C． 101g食鹽水中含有1g食鹽
• D． 20g水中溶有0.2g食鹽

Answer 1

分析 溶質(zhì)質(zhì)量分?jǐn)?shù)是溶質(zhì)質(zhì)量與溶液質(zhì)量之比，溶質(zhì)質(zhì)量分?jǐn)?shù)為1%的食鹽水，其含義是每100份質(zhì)量的食鹽水中含有1份質(zhì)量的食鹽，據(jù)此進(jìn)行分析判斷．

解答 解：A、100g水中溶有1g食鹽，所得溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)為$\frac{1g}{1g+100g}$×100%＜1%，故選項(xiàng)錯(cuò)誤．
B、99g水中溶有1g食鹽，所得溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)為$\frac{1g}{1g+99g}$×100%=1%，故選項(xiàng)正確．
C、101g食鹽水中含有1g食鹽，所得溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)為$\frac{1g}{101g}$×100%＜1%，故選項(xiàng)錯(cuò)誤．
D、20g水中溶有0.2g食鹽，所得溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)為$\frac{0.2g}{0.2g+20g}$×100%＜1%，故選項(xiàng)錯(cuò)誤．
故選：B．

點(diǎn)評(píng) 本題難度不大，理解溶質(zhì)質(zhì)量分?jǐn)?shù)的含義并能靈活運(yùn)用是正確解答本題的關(guān)鍵．