January 2015 Chemistry Regents #36-40
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Questions | Answer | Links | Explanations |
36 The table below gives the atomic mass and the abundance of the two naturally occurring isotopes of chlorine. Which numerical setup can be used to calculate the atomic mass of the element chlorine? (1) (34.97 u)(75.76) +(36.97 u)(24.24) (2) (34.97 u)(0.2424) + (36.97 u)(0.7576) (3) (34.97 u)(0.7576) + (36.97 u)(0.2424) (4) (34.97 u)(24.24) + (36.97 u)(75.76) 37 | 3 | Link | weighted average mass= (mass x % as a decimal) + (mass x % as a decimal) |
37 Which general trends in first ionization energy and electronegativity values are demonstrated by Group 15 elements as they are considered in order from top to bottom? (1) The first ionization energy decreases and the electronegativity decreases. (2) The first ionization energy increases and the electronegativity increases. (3) The first ionization energy decreases and the electronegativity increases. (4) The first ionization energy increases and the electronegativity decreases. | 1 | Link | look up the data on Table S |
38 An aluminum sample has a mass of 80.01 g and a density of 2.70 g/cm3. According to the data, to what number of significant figures should the calculated volume of the aluminum sample be expressed? (1) 1 (3) 3 (2) 2 (4) 4 | 3 | Link | division least number of sig figs...3 |
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39 Given four particle models: Which two models can be classified as elements? (1) I and II (3) II and III (2) I and IV (4) II and IV | 3 | Link | must be all the same dots |
40 After being thoroughly stirred at 10.°C, which mixture is heterogenous? (1) 25.0 g of KCl and 100. g of H2O (2) 25.0 g of KNO3 and 100. g of H2O (3) 25.0 g of NaCl and 100. g of H2O (4) 25.0 g of NaNO3 and 100. g of H2O | 2 | Link | it would have solid left so look above its line on table G |
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