June 2008 Chemistry Regents #11-20

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 

Questions

Answer Explanations
11 Which formula represents a polar molecule?
(1) Br2     (3) CH4
(2) CO2    (4) NH3
4 draw them, the asymmetrical one
12 Two solid samples each contain sulfur, oxygen, and sodium, only. These samples have the same color, melting point, density, and reaction with
an aqueous barium chloride solution. It can be concluded that the two samples are the same
(1) compound     (3) mixture
(2) element          (4) solution
1 the others answers don't make sense
13 Which equation represents a physical change?
(1) H2O(s) + 6.01 kJ  ==>H2O(l)
(2) 2H2(g) + O2(g) ==>2H2O(g) + 483.6 kJ
(3) H2(g) + I2(g) + 53.0 kJ  ==>2HI(g)
(4) N2(g) + 2O2(g) + 66.4 kJ ==> 2NO2(g)
1 phase change
14 Which liquid has the lowest vapor pressure at 65C?
(1) ethanoic acid       (3) propanone
(2) ethanol                (4) water
1 Table H
15 Which substance can not be broken down by a chemical reaction?
(1) ammonia          (3) methane
(2) argon               (4) water
2 Definition of a compound
16 In which sample is the average kinetic energy of the particles greatest?
(1) 10. mL of HCl(aq) at 25C
(2) 15 mL of HCl(aq) at 20.C
(3) 10. mL of H2O(l) at 35C
(4) 15 mL of H2O(l) at 30.C
3 Definition of Temperature   -average kinetic energy
17 A thermometer is in a beaker of water. Which statement best explains why the thermometer reading initially increases when LiBr(s) is dissolved in the water?
(1) The entropy of the LiBr(aq) is greater than the entropy of the water.
(2) The entropy of the LiBr(aq) is less than the entropy of the water.
(3) The dissolving of the LiBr(s) in water is an endothermic process.
(4) The dissolving of the LiBr(s) in water is an exothermic process.
4 Temp increases exothermic

a solid dissolving is an increase in entropy

18 Which process increases the potential energy of the particles of a sample?
(1) condensation       (3) solidification
(2) deposition            (4) vaporization
4 SLG question

       L<--G

S<-------G

S<--L

        L-->G

19 Which sample at STP has the same number of molecules as 5 liters of NO2(g) at STP?
(1) 5 grams of H2(g)
(2) 5 liters of CH4(g)
(3) 5 moles of O2(g)
(4) 5 1023 molecules of CO2(g)
2 Avagodro's Hypothesis same volumes at STP same number of molecules
20 Under which conditions of temperature and pressure does oxygen gas behave least like an ideal gas?
(1) low temperature and low pressure
(2) low temperature and high pressure
(3) high temperature and low pressure
(4) high temperature and high pressure
2 Ideal gas = ideal vacation

high temp low pressure

use opposite is says NOT

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

 
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