Direct electron transfer from a a singlet reduced species to a triplet oxidizing species is quantum-mechanically forbidden.
<h3><u>Transfer from singlet to triplet:</u></h3>
- Either an excited singlet state or an excited triplet state will occur when an electron in a molecule with a singlet ground state is stimulated (through radiation absorption) to a higher energy level.
- All electron spins in a molecule electronic state known as a singlet are coupled.
- In other words, the ground state electron and the stimulated electron's spin are still coupled (a pair of electrons in the same energy level must have opposite spins, per the Pauli exclusion principle).
- The excited electron and ground state electron are parallel in a triplet state because they are no longer coupled (same spin).
- It is less likely that a triplet state would arise when the molecule absorbs radiation since excitation to a triplet state necessitates an additional "forbidden" spin transfer.
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Answer:
(a) Ethyl acetate and hexane, and (c) methanol and methylene chloride.
Explanation:
re-crystallization is a technique used to purify solid compound. Ethyl acetate and hexane are good solvent pair for recrystallization because they are miscible with each other due to their good differences in polarity. ethyl acetate has polarity of 77 while hexane has 68.
water and diethyl ether are not good solvent pair for recrystallization because water and diethyl ether are immiscible. They have very far polarity values. water has 100 while diethyl ether has 35
Answer:
He is wrong . Most accurate is Buret .
Explanation:
The number of significant figure denotes the level of accuracy of a measurement .
Beaker can measure liquid in mL upto significant figure of 2 . That means it can measure volume in terms of 10 , 20 , 30mL etc . It can not measure 25 mL
accurately . The last figure of 28 mL is read by guess in the question . So it is not an accurate measurement .
Similarly , graduated cylinder can measure liquid upto significant figure of 3 . That means it can measure volume in terms of 11 , 22 , 33 mL etc . It can not measure 25.5 mL accurately . The last figure of 28.3 mL is read by guess in the question . So it is less accurate measurement .
Similarly , buret can measure liquid upto significant figure of 4 . That means it can measure volume in terms of 11.2 , 22.3 , 33.5 mL etc . It can not measure 25.53 mL accurately . The last figure of 28.32 mL is read by guess in the question . So it is most accurate among all the three instrument because it can measure accurately mL upto one tenth of it .
