June 2014 Chemistry Regents #31-35
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Questions | Answer | Links | Explanations |
| 31 Which notations represent different isotopes of the element sodium? (1) 32S and 34S (3) Na+ and Nao (2) S2- and S6+ (4) 22Na and 23Na | 4 | link | Isotopes have same # of protons and different # of neutrons, so the mass number is different |
| 32 Which electron configuration represents the electrons in an atom of Ga in an excited state? (I) 2-8-17-3 (3) 2-8-18-3 (2) 2-8-17-4 (4) 2-8-18-4 | 2 | link | the ground state configuration is 2-8-18-3 promote an electron to make it excited 2-8-17-4 |
| 33 Which statement describes the general trends in electronegativity and first ionization energy as the elements in Period 3 are considered in order from Na to Cl? (1) Electronegativity increases, and first ionization energy decreases. (2) Electronegativity decreases, and first ionization energy decreases. (3) Electronegativity and first ionization energy both increase. (4) Electronegativity and first ionization energy both decrease. | 3 | link | look up the values on table S |
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| 34 What is the gram-formula mass of Fe(NO3)3? (1) 146 g/mol (3) 214 g/mol (2) 194 g/mol (4) 242 g/mol | 4 | link | Fe=56 N=3 x 14=52 O=9 x 16=144 56+52+144=242g/mol |
| 35 Given the balanced equation representing a reaction: Al2(SO4)3 +6NaOH ==> 2Al(OH)3 + 3Na2SO4 The mole ratio of NaOH to Al(OH)3 is (1) 1:1 (2) 1:3 (3) 3:1 (4) 3:7 | 3 | link | THE MOLE RATIO IS THE COEFFICIENT RATIO 6NaOH: 2Al(OH)3 reduces to 3:1 |
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