Chemistry MCQ thread...

[Zishi]

Is it C? I reckon that no option is correct, but I'd go with C. :unknown:

C? How about the concentration of BiOCl?

BiOCl is a solid, so won't be included in Kp OR Kc expression.

 

[Zishi]

its a straightt forward question...remember ur Kc expression will not include water and BiOcL3

You didn't answer the previous questions you asked? Does this means that our answers were correct?

 

[xHazeMx]

Use of the Data Booklet is relevant to this question.
The bond energy of the C–H bond (438 kJ mol–1) in CH4 is typically stronger than most other
aliphatic C–H bonds. This has an effect on the first step of the propagation stage of the
reaction between CH4 and the halogen.
CH4 + X• → •CH3 + HX where X = F, Cl, Br or I
On the basis of bond energies, which statement about the reaction between CH4 and the
halogen is incorrect?
A Bromine and iodine essentially do not react with methane.
B Fluorine is so reactive that neither UV light or heat is needed.
C The order of halogen reactivity is due to the decreasing strength of the HX bond.
D The ΔH for the first propagation step is more endothermic for the chlorination of C2H6.

i guess its D, ethane is more compact so the energy will be less endothermic, am i right?

 

[maybeitwasnoone]

its a straightt forward question...remember ur Kc expression will not include water and BiOcL3

Because BiOCl is a solid?

 

[xHazeMx]

the question about Kc that hassam asked, the answer is A i m 90 % sure

 

[hassam]

bUT MS says C....YEA they were ryt....

 

[hassam]

Use of the Data Booklet is relevant to this question.
The bond energy of the C–H bond (438 kJ mol–1) in CH4 is typically stronger than most other
aliphatic C–H bonds. This has an effect on the first step of the propagation stage of the
reaction between CH4 and the halogen.
CH4 + X• → •CH3 + HX where X = F, Cl, Br or I
On the basis of bond energies, which statement about the reaction between CH4 and the
halogen is incorrect?
A Bromine and iodine essentially do not react with methane.
B Fluorine is so reactive that neither UV light or heat is needed.
C The order of halogen reactivity is due to the decreasing strength of the HX bond.
D The ΔH for the first propagation step is more endothermic for the chlorination of C2H6.

i guess its D, ethane is more compact so the energy will be less endothermic, am i right?

u r ryt..bt i dont understand...y its D

 

[maybeitwasnoone]

C? How about the concentration of BiOCl?

BiOCl is a solid, so won't be included in Kp OR Kc expression.

Oh right.

 

[maybeitwasnoone]

please explain June 03 question 2.

The answer is B, 5 moles of Hydrogen.

 

[Mssamgirl15]

Got it. Thanks.

 

[xHazeMx]

Use of the Data Booklet is relevant to this question.
The bond energy of the C–H bond (438 kJ mol–1) in CH4 is typically stronger than most other
aliphatic C–H bonds. This has an effect on the first step of the propagation stage of the
reaction between CH4 and the halogen.
CH4 + X• → •CH3 + HX where X = F, Cl, Br or I
On the basis of bond energies, which statement about the reaction between CH4 and the
halogen is incorrect?
A Bromine and iodine essentially do not react with methane.
B Fluorine is so reactive that neither UV light or heat is needed.
C The order of halogen reactivity is due to the decreasing strength of the HX bond.
D The ΔH for the first propagation step is more endothermic for the chlorination of C2H6.

i guess its D, ethane is more compact so the energy will be less endothermic, am i right?

u r ryt..bt i dont understand...y its D

bromine and chlorine dont react with CH4 under normal conditions, D is correct because in both cases one CH bond is broken so the energy is the same.
that question about Kc,is A correct ?

 

[MHHaider707]

@zishi: u mean to say that in Kc we take only compounds in aqueous phase and in Kp only gaseous compounds are taken.....right??

 

[Zishi]

@zishi: u mean to say that in Kc we take only compounds in aqueous phase and in Kp only gaseous compounds are taken.....right??

No. We only don't include solids in Kc. I'd say that question is wrong in that case. But as all the options didn't include water that's why, then, answer should be C. :Search:

 

[xHazeMx]

@zishi: u mean to say that in Kc we take only compounds in aqueous phase and in Kp only gaseous compounds are taken.....right??

No. We only don't include solids in Kc. I'd say that question is wrong in that case. But as all the options didn't include water that's why, then, answer should be C. :Search:

if BiOCl3 and water are not included then the answer should be A , right ? :%)

 

[Zishi]

@zishi: u mean to say that in Kc we take only compounds in aqueous phase and in Kp only gaseous compounds are taken.....right??

No. We only don't include solids in Kc. I'd say that question is wrong in that case. But as all the options didn't include water that's why, then, answer should be C. :Search:

if BiOCl3 and water are not included then the answer should be A , right ? :%)

Nope, answer should be C. I guess you didn't divide moles by the volume to get concentration, as in Kc, we take concentrations.

 

[xHazeMx]

Nope, answer should be C. I guess you didn't divide moles by the volume to get concentration, as in Kc, we take concentrations.

lol i really should go sleep by now

 

[Abdulrab]

http://www.xtremepapers.me/CIE/Internat ... 8_qp_1.pdf Q 23, 26, 27, 30 AND 39

PLEASE SOLVE THEM !!! THNX I DONT HAV SCREEN SHOT OPTION

please solve them !! ill be thnkful to u guys !!

 

[xHazeMx]

how would we solve that?

Use of the Data Booklet is relevant to this question.
Which element is likely to have an electronegativity similar to that of aluminium?
A barium
B beryllium
C magnesium
D strontium

 

[girlscampisra]

Magnessium because they are same period, maybe!

 

[xHazeMx]

Magnessium because they are same period, maybe!

its beryillium. the listed choices are all from group 2. so the one on the top has the highest charge density as it has the least ionic/atomic radii. so the answer is Beryillium.