Chemistry MCQ thread...

[abdullah181994]

 

[Aloo007]

dude i was tryin to figure out Q5 dont get it wats the ans? but the other Question is D as N goes from -3 to +1 and +5 to +1 changes are +4 and -4

 

[Aloo007]

@ abdullah nevermind i got how to do the other Qs aswel 38-214 divided by 2 you get -88

 

[Octahedral]

 

[hassam]

C

 

[Aloo007]

answer is 3 i dont know how to explain it but from left to right one is fromed from CH3 the other from CH2 then the third from any of the CH3 as they all are the same

 

[Abdulrab]

@ Aloo007 ow did u get the oxidation states of N in the reactants ???? please explain

 

[Saturation]

Number 35, I get that MgO and and BaO will form, but won't the MgO formed react with the NO2 (acidic oxide), forming magnesium nitrate? Please explain!
The answers B btw.

http://www.xtremepapers.me/CIE/Internat ... 7_qp_1.pdf

 

[Xthegreat]

1.2 g of an oxide MO of a metal M was dissolved in an excess sulfuric acid. 25.0 cm3 of
0.10 mol dm−3 potassium dichromate(VI) solution was required to oxidise M2+ to M3+.
What is the relative atomic mass of M?
A 52
B 56
C 64
D 80

ans : C ? yes?

 

[Aloo007]

@ abdulrab its NH4NO3 its an ioninc bond between NH4+ and NO3- get it now?

 

[Xthegreat]

Number 35, I get that MgO and and BaO will form, but won't the MgO formed react with the NO2 (acidic oxide), forming magnesium nitrate? Please explain!
The answers B btw.

http://www.xtremepapers.me/CIE/Internat ... 7_qp_1.pdf

Ba is more electropositive than Mg, hence Mg cannot displace Ba.

 

[RafaySid]

@ rafaysid hahaha it says aloo as in a patato not aleena

Oops, my bad. Lol

 

[Octahedral]

 

[RafaySid]

Hahah! I was stuck on this one for a min 15 mins today. Can anyone explain the balancing of this disproportionation reaction by oxidation numbers. I know the answer is B but plz c'mon somebody..

 

[intel1993]

hey why cant A be the answer???

 

[hassam]

YA 64 is ryt...

 

[Saturation]

Number 35, I get that MgO and and BaO will form, but won't the MgO formed react with the NO2 (acidic oxide), forming magnesium nitrate? Please explain!
The answers B btw.

http://www.xtremepapers.me/CIE/Internat ... 7_qp_1.pdf

Ba is more electropositive than Mg, hence Mg cannot displace Ba.

But doesn't the NO2 gas produced react with the MgO?

 

[kshumaila52]

ans B
I2 is is formed after gain of electron (in HIO, oxidation state of I is +1, so gain 2 electrons to form I2)
in HIO3, I is oxidise by loosing 4 electron.
to keep loss ang gain of electron same, there must be 2 mole of I2.
Best wishes for tomorrow

 

[intel1993]

hey hassam do answ my question abv.............

 

[kshumaila52]

hey why cant A be the answer???

Ans is D
already it contain 8 chiral carbon, and 4 ll more.
2ndly
A is wrong because 4 mole required,not 3( 3 for alcohol and one for acid)
B is wrong because 4(may 5) mole of H2 required, 2 for alkene, one for ketone and one(may be 2) for acid.
C is wrong, because in acidic medium, hydrolysis ll occurred