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Chemistry MCQ thread...

Varuna0911

Varuna0911

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ZohaibAsad said:
2Al +Ba(NO3)2 ---> 2Al2O3 +N2 +BaO

Stoichiometric ratio: 1:1

moles of N2 = 0.003

volume = 0.003 x 24 x 1000 = 72 cm^3

B.



Next time please post the link to the question paper, saves time.
Click to expand...

thanks, i did post the link but I think it didn't appear :(
 
magnesium

magnesium

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Carbon monoxide, CO, nitrogen monoxide, NO, and sulfur dioxide, SO2, may all be present in the
exhaust fumes from a car engine.
Which reaction concerning these compounds occurs in the atmosphere?
A CO is spontaneously oxidised to CO2
B NO2 is reduced to NO by CO
C NO2 is reduced to NO by SO2
D SO2 is oxidised to SO3 by CO2
 
messi10

messi10

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magnesium said:
Carbon monoxide, CO, nitrogen monoxide, NO, and sulfur dioxide, SO2, may all be present in the
exhaust fumes from a car engine.
Which reaction concerning these compounds occurs in the atmosphere?
A CO is spontaneously oxidised to CO2
B NO2 is reduced to NO by CO
C NO2 is reduced to NO by SO2
D SO2 is oxidised to SO3 by CO2
Click to expand...

These are reactions that occur, whenever there is car combustion reactions, recall these reactions:
1. NO2 + CO => N2 + CO2
2. NO + SO2 => N2 + SO3
3. NO2 + SO2 => NO + SO3 (This one rarely occurs)

Discussing all the options:
A - CO is not SPONTANEOUSLY oxidized
B - NO2 is not reduced to NO by CO, in fact its reduced to N2
C - This one seems correct as NO2 is reduced from +4 oxidation state to +2 by SO2
D - CO2 has no role in it.

Hope this helps.
 
ZohaibAsad

ZohaibAsad

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NouranAyman said:
http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_s10_qp_11.pdf
Q 4 , 6 , 8 and 9 pleaseee
Click to expand...

Q4: First identify which reactions are endothermic and which are exothermic, endothermic are P and S so they should be the last two options because bond breaking is positive, this only happens in B and C so options A and D eliminated. Out of P and S it is quite obvious that breaking the four C-H bonds in methane will require more energy than breaking 1 Br-Br bond hence S should be the most positive, that only happens in C so that's the answer.
 
babycry

babycry

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magnesium said:
Carbon monoxide, CO, nitrogen monoxide, NO, and sulfur dioxide, SO2, may all be present in the
exhaust fumes from a car engine.
Which reaction concerning these compounds occurs in the atmosphere?
A CO is spontaneously oxidised to CO2
B NO2 is reduced to NO by CO
C NO2 is reduced to NO by SO2
D SO2 is oxidised to SO3 by CO2
Click to expand...
from ur knowledge u know that SO2 is a reducing agent. in the contact process u need special conditions e.g catalyst e.t.c to oxidise the SO2 to SO3. hence the answer is C
 
Z

zephyr86

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hi,can anyone help with this question?
20 The formula CH3 can represent an anion, a cation or a free radical. Species with the molecular
formula CH3 can act as an electrophile, a free radical or a nucleophile depending on the number
of outer shell electrons on the central carbon atom.
How many outer shell electrons must be present for CH3 to act in these different ways?
CH3 as an CH3 as a CH3 as a
electrophile free radical nucleophile

A 6 7 8
B 6 8 7
C 7 6 8
D 8 7 6
 
I

Iadmireblue

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Draw a vector diagram pointing out the dipoles eg in A it would be an arrow from C to CL and hence you draw four arrows.Do it for all four structures.The one with the least arrows give you the largest dipole
 
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