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USA Physics and Chemistry Contests
National Chemistry Olympiad
2013 National Chemistry Olympiad
54
54
Part of
2013 National Chemistry Olympiad
Problems
(1)
2013 USNCO Problem 54: Sigma and Pi bonds
Source:
4/19/2013
How many sigma
(
σ
)
(\sigma)
(
σ
)
and pi
(
π
)
(\pi)
(
π
)
bonds are in a molecule of ethyne (acetylene), \ce{HCCH}?
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(
A
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1
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1
π
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(
B
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2
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1
π
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(
C
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2
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3
π
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(
D
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3
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<span class='latex-bold'>(A) </span> 1 \sigma \text{ and } 1 \pi \qquad<span class='latex-bold'>(B) </span>2 \sigma \text{ and } 1 \pi \qquad<span class='latex-bold'>(C) </span>2 \sigma \text{ and } 3\pi \qquad<span class='latex-bold'>(D) </span>3 \sigma \text{ and } 2 \pi\qquad
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(
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1
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1
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(
B
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2
σ
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1
π
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(
C
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2
σ
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3
π
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(
D
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3
σ
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2
π