August 2006 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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Answer Explanations
21 A substance is classified as an electrolyte because
(1) it has a high melting point
(2) it contains covalent bonds
(3) its aqueous solution conducts an electric current
(4) its aqueous solution has a pH value of 7
3 definition of electrolyte
22 Half-reactions can be written to represent all
(1) double-replacement reactions
(2) neutralization reactions
(3) fission and fusion reactions
(4) oxidation and reduction reactions
4 half reactions are oxidation reduction reactions
1 isomers same formula different structure

count atoms

24 Given the balanced equation representing a redox reaction:
2Al + 3Cu2+ --> 2Al3+ + 3Cu
Which statement is true about this reaction?
(1) Each Al loses 2e- and each Cu2+ gains 3e-
(2) Each Al loses 3e- and each Cu2+ gains 2e-
(3) Each Al3+ gains 2e- and each Cu loses 3e-
(4) Each Al3+ gains 3e- and each Cu loses 2e-
2 Al charge goes up oxidation, lose electrons 0-->+3 is 3 electrons

Cu2+ charge goes down reduction, gain electrons, +2 to 0 is 2 electrons

25 Which conversion of energy always occurs in a voltaic cell?
(1) light energy to chemical energy
(2) electrical energy to chemical energy
(3) chemical energy to light energy
(4) chemical energy to electrical energy
4 voltaic is a battery, chemical to electrical
26 The compound NaOH(s) dissolves in water to yield
(1) hydroxide ions as the only negative ions
(2) hydroxide ions as the only positive ions
(3) hydronium ions as the only negative ions
(4) hydronium ions as the only positive ions
1 Arrhenius base definition
3 acid and base makes salt and water
4 Use table N (for decay) and table O (for notation)
29 Atoms of one element are converted to atoms of another element through
(1) fermentation    (3) polymerization
(2) oxidation         (4) transmutation
4 Definition of transmutation
30 An atom of potassium-37 and an atom of potassium-42 differ in their total number of
(1) electrons     (3) protons
(2) neutrons      (4) positrons
2 They are isotopes, so the # of neutrons


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