Chemistry MCQ thread...

[xHazeMx]

20 When gaseous chemicals are transported by road or by rail they are classified as follows.
flammable non-flammable poisonous
Which commonly transported gas is non-flammable?
A butane
B hydrogen
C oxygen
D propene

Why is oxygen non-flammable?

C , others are flammable

 

[Mssamgirl15]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s08_qp_1.pdf

Guys, May/June 2008 question number 6 or click on the link above.
Please answer this question. I can't upload a screenshot for some reason. :/

You used PV=nRT?

Dude, I tried to use PV=nRt but the answer I am getting is 2.72 into 10 raise to the power -3. Could you pretty please explain?

 

[xHazeMx]

its C and im getting D :%) what are the values to be taken in PV=nRT ?
uploaded it so everyone can share his answer

 

[maybeitwasnoone]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s08_qp_1.pdf

Guys, May/June 2008 question number 6 or click on the link above.
Please answer this question. I can't upload a screenshot for some reason. :/

You used PV=nRT?

Dude, I tried to use PV=nRt but the answer I am getting is 2.72 into 10 raise to the power -3. Could you pretty please explain?

Thats how I did it, and took it to the closest value there after converting to dm3.
Dude?

 

[Zishi]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9701%20-%20Chemistry/9701_s08_qp_1.pdf

Guys, May/June 2008 question number 6 or click on the link above.
Please answer this question. I can't upload a screenshot for some reason. :/

You used PV=nRT?

Dude, I tried to use PV=nRt but the answer I am getting is 2.72 into 10 raise to the power -3. Could you pretty please explain?

That's volume in m^3, you've to convert it into dm^3

 

[maybeitwasnoone]

its C and im getting D :%) what are the values to be taken in PV=nRT ?
uploaded it so everyone can share his answer

Using the density you could find the no. of moles, the rest, the values are right in front of you.

 

[hassam]

Which statement concerning the lattice structure of graphite and diamond is incorrect?
A All C–C bonds in graphite and diamond are formed from sp3–sp3 overlap.
B Graphite is energetically more stable than diamond.
C The bond energy of the C–C bonds in graphite is greater than that in diamond.
D The C–C–C bond angle between nearest neighbours is smaller in diamond than in
graphite
is it A ryt...i did by elimination

 

[Zishi]

Which statement concerning the lattice structure of graphite and diamond is incorrect?
A All C–C bonds in graphite and diamond are formed from sp3–sp3 overlap.
B Graphite is energetically more stable than diamond.
C The bond energy of the C–C bonds in graphite is greater than that in diamond.
D The C–C–C bond angle between nearest neighbours is smaller in diamond than in
graphite
is it A ryt...i did by elimination

Yes. It's A.

 

[xHazeMx]

Which statement concerning the lattice structure of graphite and diamond is incorrect?
A All C–C bonds in graphite and diamond are formed from sp3–sp3 overlap.
B Graphite is energetically more stable than diamond.
C The bond energy of the C–C bonds in graphite is greater than that in diamond.
D The C–C–C bond angle between nearest neighbours is smaller in diamond than in
graphite
is it A ryt...i did by elimination

i m getting A by elimination too

 

[hassam]

 

[maybeitwasnoone]

Is it B?

 

[xHazeMx]

B right ?

 

[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.

 

[hassam]

how it cn be B yar...u used moles i guess and not concentrations

 

[Zishi]

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

 

[Zishi]

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 it's A.

 

[maybeitwasnoone]

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

C? How about the concentration of BiOCl?

 

[smartangel]

please explain June 03 question 2.

 

[MHHaider707]

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.

Its A!!

 

[hassam]

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