January 2011 Chemistry Regents #31-40
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Questions | Answer | Explanations |
| 31 Which electron configuration represents the electrons of an atom in an excited state? (1) 2-1 (3) 2-8-7 (2) 2-7-4 (4) 2-4 | 2 | look for a gap in the configuration Hint-add up all the electrons, if it doesn't match up on the PT it is excited |
| 32 What is the total number of neutrons in an atom of O-18? (1) 18 (3) 10 (2) 16 (4) 8 | 3 | mass #=16 subtract the 8 protons leaving 8 neutrons |
| 33 What is the net charge of an ion that has 8 protons, 9 neutrons, and 10 electrons? (1) 1+ (3) 1− (2) 2+ (4) 2− | 4 | 2 more electrons than protons so 2- |
| 34 Which element is malleable and a good conductor of electricity at STP? (1) argon (3) iodine (2) carbon (4) silver | 4 | the metal |
| 35 Which element has chemical properties that are most similar to the chemical properties of sodium? (1) beryllium (3) lithium (2) calcium (4) magnesium | 3 | same group |
| 36 If an element, X, can form an oxide that has theformula X2O3, then element X would most likely be located on the Periodic Table in the same group as (1) Ba (3) In (2) Cd (4) Na | 3 | X2O3 X is 3+ so, group 13 |
| 37 What is the total mass of KNO3 that must be dissolved in 50. grams of H2O at 60.°C to make a saturated solution? (1) 32 g (3) 64 g (2) 53 g (4) 106 g | 2 | table G, but it reads 50.g of water so divide the amount on the table by 2 |
| 38 Which statement describes the general trends in electronegativity and metallic properties as the elements in Period 2 are considered in order of increasing atomic number? (1) Both electronegativity and metallic properties decrease. (2) Both electronegativity and metallic properties increase. (3) Electronegativity decreases and metallic properties increase. (4) Electronegativity increases and metallic properties decrease. | 4 | electron negativity increases (heading to Fluorine) metallic character decreases you are leaving the metals |
| 39 Which balanced equation represents a single replacement reaction? (1) Mg + 2AgNO3 → Mg(NO3)2+ 2Ag (2) 2Mg + O2 → 2MgO (3) MgCO3 → MgO + CO2 (4) MgCl2+ 2AgNO3 → 2AgCl + Mg(NO3)2 | 1 | A+BC-->AC + B |
| 40 Given the balanced equation representing a reaction: Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g) This reaction occurs more quickly when powdered iron is used instead of a single piece of iron of the same mass because the powdered iron (1) acts as a better catalyst than the single piece of iron (2) absorbs less energy than the single piece of iron (3) has a greater surface area than the single piece of iron (4) is more metallic than the single piece of iron | 3 | more surface area more collisions |