January 2007 Chemistry Regents #21-30
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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.
|4||equilibrium=con con Requal
concentrations constant Rates are equal
|4||5 carbons pent-
acid -anoic acid
|3||hydrocarbon =only hydrogen and
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
|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
|1||same formula (atoms) different structure are isomers|
|26 Given the balanced equation representing a
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
|4||substitution 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
|3||more randomness (entropy) and lower energy|
|1||3 bonds (3 x 2electrons)|
|29 Which compound has hydrogen bonding
between its molecules?
(1) CH4 (3) KH
(2) CaH2 (4) NH3
|4||H-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–
|3||Base= OH- hydroxide|
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