Victory for the ACT Student Text 15e

S CIENCE Q UIZZES • 337

TIMED QUIZ (16 items; 15 minutes)

DIRECTIONS: Each passage below is followed by several items. After reading a passage, choose the best answer to each item. You may refer to the passages as often as necessary. You are NOT permitted the use of a calculator. Answers are on p. 442. Passage I The chart below shows an outline for a common means of analyzing a sample solution for various dissolved cations (positive ions). Ions above the horizontal arrows are those that are suspected to be present in the sample solution; the substances in the boxes are the reagents added as tests (0.3 M H is acidic, NH OH 4 is alkaline); the products shown next to the arrows ’‘‹–‹‰ †‘™™ƒ”† ƒ”‡ •‘Ž‹† ’”‡…‹’‹–ƒ–‡• ”‡•—Ž–‹‰ ˆ”‘ –Š‡ –‡•–•Ǥ ‡•–• ˆ‘” •’‡…‹ϐ‹…‹‘• ‡‡† ‘– always start from the beginning of the sequence.

1. According to the chart, which precipitate indicates if silver ( Ag ) is present in the sample? A. AgCl B. Ag C. CuS D. ZnS 2. If a solution containing silver (Ag) nitrate and cupric (Cu) nitrate, both compounds known to dissociate into ions in solution, is tested according to this scheme, an experimenter will: Ǥ ϐ‹”•– ‘„•‡”˜‡ ‰ Ž ‘ –”‡ƒ–‡– with Cl , and next observe CuS on treatment with acidic H S 2 . Ǥ ϐ‹”•– ‘„•‡”˜‡ — ‘ –”‡ƒ–‡– with Cl , and next observe AgCl on treatment with acidic H S 2 . Ǥ ϐ‹”•– ‘„•‡”˜‡ CaCO 3 on treatment with CO 3 2 , and next observe AgCl on treatment with Cl . J. observe no reactions, since the scheme does not test for nitrate.

3. What is the minimum number of tests ‡…‡••ƒ”› –‘…‘ϐ‹” –Š‡…‘’‘•‹–‹‘ ‘ˆ an unknown solution that contains either Cu 2 or Zn 2 , but not both? A. One B. Two C. Three D. Four