January 2007 Chemistry Regents #21-30

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

 

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AnswerExplanations
21 Which statement must be true for any chemical reaction at equilibrium?
(1) The concentration of the products is greater than the concentration of the reactants.
(2) The concentration of the products is less than the concentration of the reactants.
(3) The concentration of the products and the concentration of the reactants are equal.
(4) The concentration of the products and the concentration of the reactants are constant.		4equilibrium=con con Requal

 

concentrations constant Rates are equal

45 carbons  pent-

 acid   -anoic acid  

3hydrocarbon =only hydrogen and carbon

unsaturated (contains a double or triple bond)

24 Which group of nuclear emissions is listed in order of increasing charge?
(1) alpha particle, beta particle, gamma radiation
(2) gamma radiation, alpha particle, beta particle
(3) positron, alpha particle, neutron
(4) neutron, positron, alpha particle		4neutron 0

positron +1

alpha +2

25 Two substances have different physical and chemical properties. Both substances have
molecules that contain two carbon atoms, one oxygen atom, and six hydrogen atoms. These two substances must be
(1) isomers of each other
(2) isotopes of each other
(3) the same compound
(4) the same hydrocarbon		1same formula (atoms) different structure  are isomers
26 Given the balanced equation representing a reaction:
CH3CH2CH3 + Br2==> CH3CH2CH2Br + HBr
This organic reaction is best classified as
(1) an addition reaction
(2) an esterification reaction
(3) a polymerization reaction
(4) a substitution reaction		4substitution propane is saturated
27 In terms of energy and entropy, systems in nature tend to undergo changes toward
(1) higher energy and higher entropy
(2) higher energy and lower entropy
(3) lower energy and higher entropy
(4) lower energy and lower entropy		3more randomness (entropy) and lower energy
13 bonds (3 x 2electrons)
29 Which compound has hydrogen bonding between its molecules?
(1) CH4     (3) KH
(2) CaH2   (4) NH3		4H-bonding   H with F, O, or N
30 Which ion is the only negative ion produced by an Arrhenius base in water?
(1) NO3–    (3) OH–
(2) Cl–        (4) H–		3Base= OH- hydroxide

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

 
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