הקשר הכימי -2019

Discuss, Learn and be Happy דיון בשאלות

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In the פאי סטאר* of H2CO, the orbital coefficient will be

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שאלה #26969

		Higher in O.
		Higher in C.
done		Same in both.

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The correlation energy is defined as:

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שאלה #26970

done		The energy difference between Full CI and HF.
		The instantaneous repulsion interaction between two electrons.
		The energy difference between a complete and a minimal basis set.

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?

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שאלה #26971

		A
sentiment_very_satisfied		B
		C

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According to Hammond’s postulate, which one is not correct? A more exothermic reaction will give an earlier transition state.

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שאלה #26972

		A more endothermic reaction will give a larger activation energy.
		A more exothermic reaction will give an earlier transition state.
done		A more endothermic reaction will give a smaller imaginary frequency.

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Which one of these is not an observable?

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שאלה #26973

		Position.
done		Atomic charge.
		Electronic density.

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Which of these is correct for London forces?

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שאלה #26974

		Heitler-London interaction is important.
done		Polarizability is important.
		Charge transfer is important.

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Which one is correct according to Curtin-Hammett? The relative activation energies define the selectivity.

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שאלה #26975

		The relative activation energies define the selectivity.
		More exothermic reactions generate more products.
done		The selectivity depends exponentially on the energies of the transition states.

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Which one is correct:

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שאלה #26976

		Two isothermal reactions (same דלתא Grx) will have the same activation energy.
		A more exothermic reaction is faster.
done		An exothermic reaction can be barrierless.

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The transition state is defined by:

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שאלה #26977

		An order two saddle point.
		One or more positive frequencies.
done		Only one imaginary frequency.

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According to the Jahn Teller effect:

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שאלה #26978

		Benzene is hexagonal.
done		Cyclobutadiene is rectangular.
		Cyclopropene cation is triangular.

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