June 2008 Chemistry Regents #11-20
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|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)
|14 Which liquid has the lowest vapor pressure at 65°C?
(1) ethanoic acid (3) propanone
(2) ethanol (4) water
|15 Which substance can not be broken down by a chemical
(1) ammonia (3) methane
(2) argon (4) water
|2||Definition of a compound|
|16 In which sample is the average kinetic energy of the
(1) 10. mL of HCl(aq) at 25°C
(2) 15 mL of HCl(aq) at 20.°C
(3) 10. mL of H2O(l) at 35°C
(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
|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
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