P1 MCQ's preparation thread for chemistry ONLY!!!!

[hope4thebest]

its asking about cis trans isomers ....i am not really sure but i think it means 2 isomers making up a cis trans pair are considered as one cis trans isomer ...since there are three double bonds so there will be three pairs of cis trans isomers

Ans is C : 8

 

[Obsidian Fl1ght]

Which statements abt the reaction of solid NaBr and concentrated H2SO4 is correct?
1 HBr is a product
2 Sulfuric Acid is oxidised to SO2
3 Bromide ions are reduced to Bromine

Answer is D.
SHouldn't it be A?

 

[Obsidian Fl1ght]

s_11_qp12
Q11... Help appreciated.

 

[Student12]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_13.pdf
Q7(B), 11(B), 15(B), 24(A), 37(A)
HEEEEEEEEEEEEELP !

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q4(C), 8(C), 26(A), 36(D)
HELLLLLLLLLLLLLLLLLLLLLLLP !

 

[1357911]

Which statements abt the reaction of solid NaBr and concentrated H2SO4 is correct?
1 HBr is a product
2 Sulfuric Acid is oxidised to SO2
3 Bromide ions are reduced to Bromine

Answer is D.
SHouldn't it be A?

Write the equation first
NaBr+H2SO4 gives Na2SO4 and HBr. Here The bromide ions are not reduced to bromine but remain as bromine ions. And sulphuric acid is not oxidised to sulphur dioxide.

 

[Student12]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf
Q7(C), 11(C), 23(B), 33(D), 36(A), 38(D), 40(D)

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_11.pdf
Q4(D), 5(A), 9(B), 10(B), 12(C), 36(D)

HELPPPP ! In detail please..

 

[hope4thebest]

Which statements abt the reaction of solid NaBr and concentrated H2SO4 is correct?
1 HBr is a product
2 Sulfuric Acid is oxidised to SO2
3 Bromide ions are reduced to Bromine

Answer is D.
SHouldn't it be A?

No A is incorrect.Sulfuric acid itself is a strong oxidising agent.It won't be oxidised but would oxidise Br ions.3rd point is also false.Bromine ions are oxidised not reduced.(change in ox.state from -1 to 0)

 

[1357911]

Oct/Nov 2011 varient 11 Q-2 can somebody help????????

 

[Student12]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w10_qp_12.pdf Q7 (A), 8(D), 11(C), 22(C), 28(B), 39(A)
HELPPPPPPPPPPPPPPPP !

 

[Obsidian Fl1ght]

No A is correct.Sulfuric acid itself is a strong oxidising agent.It won't be oxidised but would oxidise Br ions.3rd point is also false.Bromine ions are oxidised not reduced.(change in ox.state from -1 to 0)

Yeah I chose A. Imagine my surprise when I see the answer's D.
Maybe it has something to do with NaBr being in solid state?
EDIT after sudden realisation: See below

Which statements abt the reaction of solid NaBr and concentrated H2SO4 is correct?
1 HBr is a product
2 Sulfuric Acid is oxidised to SO2
3 Bromide ions are reduced to Bromine

Answer is D.
SHouldn't it be A?

Write the equation first


NaBr+H2SO4 gives Na2SO4 and HBr. Here The bromide ions are not reduced to bromine but remain as bromine ions. And sulphuric acid is not oxidised to sulphur dioxide.

Ur right. But we've learnt that HBr is a sufficiently strong RA to... yeah ur right.
This is a trick question.
Bromide ions can NEVER be reduced to Bromine.
Oxidation state will change from -1 to 0 (Oxidation)
And H2SO4 to S is reduction.
Hey, thanks.

 

[1357911]

IS 1357911 ryt or hopeforthebest ryt? Im sorry i didnt understand u

 

[Sajeeb Chowdhury]

cn ny 1 solve this

 

[Obsidian Fl1ght]

Which statements abt the reaction of solid NaBr and concentrated H2SO4 is correct?
1 HBr is a product
2 Sulfuric Acid is oxidised to SO2
3 Bromide ions are reduced to Bromine

Answer is D.
SHouldn't it be A?

Write the equation first
NaBr+H2SO4 gives Na2SO4 and HBr. Here The bromide ions are not reduced to bromine but remain as bromine ions. And sulphuric acid is not oxidised to sulphur dioxide.

I've another prob:
s_11_qp12
Q35.
How can we validate A as being correct?

And Q11.

 

[Obsidian Fl1ght]

IS 1357911 ryt or hopeforthebest ryt? Im sorry i didnt understand u

I apologize I wasn't clear enough.
Technically both of you are right.
hopeforthebest's right in the sense that during the aforementioned reaction, Bromide ions are oxidised to Bromine gas while H2SO4 is reduced to SO2.
It was a trick question... The switched the words "oxidised" and "reduced" between Bromide ions nd H2SO4.
And you would've gotten the mark so ur right in that context.

 

[1357911]

Thanks.

 

[Mayedah]

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_12.pdf
Mcq 28 anyone ?

 

[Obsidian Fl1ght]

Thanks.

Ur welcome

 

[1357911]

s_11_qp12
Q35.
Nitrogen ions are reduced to nitrogen atoms.NaOCl is a reducing agent(bleach). And NaCl gives a white precipitate with Silver nitrate.(Cations and anions Tests)

 

[Sajeeb Chowdhury]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s12_qp_12.pdf
Mcq 28 anyone ?

alright first this is chemistry we r talking abut.......... there r gonna be repetations and patterns better momorize them...... it works fr me....

 

[1357911]

oct/nov 11 varient 11 q-9
Please help???????