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举一反三
【单选题】已知下列单键伸缩振动中 C-C C-N C-O 键力常数 k /(N·cm -1 ) 4.5 5.8 5.0 吸收峰波长 λ/μm 6 6.46 6.85 则 C-C, C-N, C-O 键振动能级之差 ⊿ E 顺序为 ( )
A.
C-C > C-N > C-O
B.
C-N > C-O > C-C
C.
C-C > C-O > C-N
D.
C-O > C-N > C-C
【单选题】已知 C—H 键的键力常数 5.0 N/cm ,则 C—H 振动吸收峰频率为
A.
1523 cm -1
B.
2523 cm -1
C.
2045 cm -1
D.
3045 cm -1
【单选题】Passage One Gravity is a slippery beast. We don’t know how strong it is, how it works or how fast its effects move. But this year we made progress. October saw the most accurate measurem...
A.
Newton and Einstein had similar opinions on the speed of gravity
B.
the author of the passage is in favor of Einstein’s thought about the speed of gravity
C.
astronomers think that both Newton and Einstein were wrong on the speed of gravity
D.
Newton’s thought about the gravitational effect is out of date
【单选题】Gravity is a slippery beast. We don’t know how strong it is, how it works or how fast its effects move. But this year we made progress. October saw the most accurate measurement yet of Newton’s gravit...
A.
two things far apart might vibrate in unison
B.
the ripples in space-time are only imagined
C.
there exist gravitational waves
D.
abrupt, violent cosmic events lead to gravitational waves