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June 2006 Chemistry Regents #11-20
Highlight to reveal answers and explanations
Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 |
Questions | Answer | Explanations |
| 11 Which formula represents a nonpolar molecule? (1) CH4 (3) H2O (2) HCl (4) NH3 | 1 | draw them the symmetrical one |
| 12 Which changes occur as a cadmium atom, Cd, becomes a cadmium ion, Cd2+? (1) The Cd atom gains two electrons and its radius decreases. (2) The Cd atom gains two electrons and its radius increases. (3) The Cd atom loses two electrons and its radius decreases. (4) The Cd atom loses two electrons and its radius increases. | 3 | loses 2 electrons and gets smaller |
| 13 Which element has atoms with the greatest attraction for electrons in a chemical bond? (1) beryllium (3) lithium (2) fluorine (4) oxygen | 2 | Definition of electronegativity Table S |
| 14 Two substances, A and Z, are to be identified. Substance A can not be broken down by a chemical change. Substance Z can be broken down by a chemical change. What can be concluded about these substances? (1) Both substances are elements. (2) Both substances are compounds. (3) Substance A is an element and substance Z is a compound. (4) Substance A is a compound and substance Z is an element. | 3 | Definition of element and compound |
| 15 Which ion, when combined with chloride ions, Cl-, forms an insoluble substance in water? (1) Fe2+ (3) Pb2+ (2) Mg2+ (4) Zn2+ | 3 | TABLE F insoluble |
| 16 Molarity is defined as the (1) moles of solute per kilogram of solvent (2) moles of solute per liter of solution (3) mass of a solution (4) volume of a solvent | 2 | Table T |
| 17 Which formula represents a hydrocarbon? (1) CH3CH2CH2CHO (2) CH3CH2CH2CH3 (3) CH3CH2CH2COOH (4) CH3CH2COOCH3 | 2 | hydrocarbons only H and C |
| 18 Which expression represents the ΔH for a chemical reaction in terms of the potential energy, PE, of its products and reactants? (1) PE of products + PE of reactants (2) PE of products – PE of reactants (3) PE of products × PE of reactants (4) PE of products ÷ PE of reactants | 2 | ΔH=PE of products – PE of reactants exothermic is neg endothermic is + |
| 19 Which balanced equation represents an endothermic reaction? (1) C(s) + O2(g) → CO2(g) (2) CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) (3) N2(g) + 3H2(g) → 2NH3(g) (4) N2(g) + O2(g) → 2NO(g) | 4 | See Table H |
| 20 Which formula represents propyne? (1) C3H4 (3) C5H8 (2) C3H6 (4) C5H10 | 1 | 3 carbons use CnH2n-2 Table Q |
Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 |
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