August 2017 Chemistry Regents #21-25
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Questions | Answer | Links | Explanations |
21 At STP, a 12.0-liter sample of CH4(g) has the same total number of molecules as (1) 6.0 L of H2(g) at STP (2) 12.0 L of CO2(g) at STP (3) 18.0 L of HCl(g) at STP (4) 24.0 L of O2(g) at STP | 2 | same volume of a GAS same number of molecules | |
22 At standard pressure, during which physical change does the potential energy decrease? (1) liquid to gas (3) solid to gas (2) liquid to solid (4) solid to liquid | 2 | S...L..G question L-->G S<--L S---->G S---->L | |
23 Which equation represents a chemical equilibrium? (1) N2(ℓ) <=> N2(g) (2) 2NO2(g) <=>N2O4(g) (3) CO2(s) <=>CO2(g) (4) NH3(ℓ) <=> NH3(g) | 2 | needs different substance formed | |
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24 The amount of randomness of the atoms in a system is an indication of the (1) entropy of the system (2) polarity of the system (3) excited state of the atoms (4) ground state of the atoms | 1 | definition of entropy | |
25 When a sample of Ca(s) loses 1 mole of electrons in a reaction with a sample of O2(g), the oxygen (1) loses 1 mole of electrons (2) loses 2 moles of electrons (3) gains 1 mole of electrons (4) gains 2 moles of electrons | 3 | conservation of mass and charge lose equals gain | |
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