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第Ⅰ卷 一、选择题(每小题3分,共51分) (1)我国领土面积约是9.60×10~6千米~2。近似数9.60×10~6的有效数字的个数为()。 (A)2(B)3(C)6(D)7 (2)计算(-3x~2)~3的结果是()。 (A)-9x~6 (B)-27x~5 (C)-27x~6 (D)-9x~6 (3)将浓度为5％的食盐溶液400克与浓度为8％的食盐溶液100克混合后所得到的溶液的浓度为x,则()。 (A)x<5.5％ (B)5.5％ 6.5％ (4)在实数范围内,下列语句正确的是()。
Volume I I. Multiple-choice questions (3 points for each question, a total of 51 points) (1) The territorial area in China is about 9.60×10~6 km~2. The number of significant figures for the approximate number 9.60×10~6 is (). (A) 2 (B) 3 (C) 6 (D) 7 (2) The result of the calculation (-3x ~ 2) ~ 3 is (). (A)-9x~6 (B)-27x~5 (C)-27x~6 (D)-9x~6 (3) 400g salt solution with 5% concentration and 8% salt solution 100 The concentration of the resulting solution after mixing is x, then (). (A) x <5.5% (B) 5.5% 6.5% (4) In the real number range, the following statement is correct ().