the P680 chlorophyll A molecule of photosystem II

a. oxidize glucose
b. oxidize water
c. best absorbs light with a wavelength of 700nm
d. provides electrons that reduce NADH
e. more than one of above

- I'm not sure if Photosystem II oxidize water, and i'm ambiguous between a,d


which of following pairs gives the bond with the least ionic character?
a. Cs and F
b. O and H
c. C and C
d. C and Cl
e. C and N

- and explain me why?




which of the following has the lowest boiling point?
a. n-hexane
b. 2-methylheptane
c. 3-methylhexane
d. 2-methylpentane
e. 2-hexanol

- BP increase as MW, Intermolecular force increase, so I think it's either a or d which has the least carbons than other (e is strong since H-bond)
but what's the correct answer?


thank you

[quote=gomawum;6102022]the P680 chlorophyll A molecule of photosystem II

a. oxidize glucose
b. oxidize water
c. best absorbs light with a wavelength of 700nm
d. provides electrons that reduce NADH
e. more than one of above

Photosystem II: P680 is a strong oxidizing agent and oxidizes water. water is split into 2 hydrogen atoms and an oxygen atom.

2) C-C has the least ionic character. Ionic character is the measure between electronegativity.

3) The answer is D because branching decrease boiling pt.

which of following pairs gives the bond with the least ionic character?
a. Cs and F
b. O and H
c. C and C
d. C and Cl
e. C and N

- and explain me why?


Answer C.
because C-C bond is a nonpolar covalent bond since both the atoms have the same electronegativity.

which of the following has the lowest boiling point?
a. n-hexane
b. 2-methylheptane
c. 3-methylhexane
d. 2-methylpentane
e. 2-hexanol


Answer D. Remember that B.P. increases with increase in chain length, and decreases with increase in branching. and in the case of 2-hexanol, hydrogen bonding increases the B.P.

the following is the order of increasing B.p.:
2-methylpentane< n-hexane<3-methylhexane<2-methylheptane<2-hexanol

but why the substitued heptane has higher bp than hexane and pentane?
does it have to do with the conformation structure?

but why the substitued heptane has higher bp than hexane and pentane?
does it have to do with the conformation structure?

the substitute heptane is composed of 8 carbons.

2-methylpentane & n-hexane
are both stuctrual isomers of C6H14, however as i mentioned earlier increas in branching causes a decrease in B.P. thus 2-methylpentane has a lower B.P. than n-hexane.

3-methylhexane = C7H16
2-methylheptane= C8H18

increasing the chain length ( in other words the back bone chain is increases) causes a increase in B.P., thus 3-methylhexane has a lower B.P than 2-methylheptane (because C6<C7<C8)

and finally in 2-hexanol there is Hydrogen bonding :eek: thus the highest B.P.

hope this helps. :o

very clear explanation thank you!