January 2009 Chemistry Regents #11-20
Highlight to reveal answers and explanations
Questions | Answer | Explanations |
| 11 During all chemical reactions, mass, energy, and charge are (1) absorbed (3) formed (2) conserved (4) released | 2 | conserved (always on test) |
| 12 Which formula represents a molecular compound? (1) Kr (3) N2O4 (2) LiOH (4) NaI | 3 | molecular = covalent (2 nonmetals) |
| 13 The bonds in BaO are best described as (1) covalent, because valence electrons are shared (2) covalent, because valence electrons are transferred (3) ionic, because valence electrons are shared (4) ionic, because valence electrons are transferred | 4 | ionic, transferred |
| 14 In which sample of water do the molecules have the highest average kinetic energy? (1) 20. mL at 100.°C (3) 60. mL at 60.°C (2) 40. mL at 80.°C (4) 80. mL at 40.°C | 1 | highest temperature |
| 15 Which compound is insoluble in water? (1) calcium bromide (3) silver bromide (2) potassium bromide (4) sodium bromide | 3 | TABLE F |
| 16 Which element is a brittle solid with low conductivity at STP? (1) sulfur (3) argon (2) sodium (4) aluminum | 1 | nonmetal, not Argon it is a gas |
| 17 Which two samples of gas at STP contain the same total number of molecules? (1) 1 L of CO(g) and 0.5 L of N2(g) (2) 2 L of CO(g) and 0.5 L of NH3(g) (3) 1 L of H2(g) and 2 L of Cl2(g) (4) 2 L of H2(g) and 2 L of Cl2(g) | 4 | the 2 gases with the same volume (Avogadro's Hypothesis) |
| 18 A reaction is most likely to occur when reactant particles collide with (1) proper energy, only (2) proper orientation, only (3) both proper energy and proper orientation (4) neither proper energy nor proper orientation | 3 | both are need for a reaction to occur |
| 19 The net energy released or absorbed during a reversible chemical reaction is equal to (1) the activation energy of the endothermic reaction (2) the activation energy of the exothermic reaction (3) the difference between the potential energy of the products and the potential energy of the reactants (4) the sum of the potential energy of the products and the potential energy of the reactants | 3 | heat of reaction or C |
| 20 A catalyst lowers the activation energy of a reaction by (1) providing an alternate reaction pathway (2) decreasing the heat of reaction (3) increasing the mass of the reactants (4) changing the mole ratio of the reactants | 1 | definition of catalyst |