chem mcq...

MHHaider707

MHHaider707

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Option A is No3 which can not be an ammonium compound!!

B is Nitric acid so it can not be the right answer!!

D is N2H4O3 which can also be written as NH4NO3 which is an ammonium compound!!!!

now Q says that on reaction with alkali a gas is produced which turns damp litmus blue which is a characteristic of NH3!!

now you have to choose that option which will react with alkali to give ammonia!!!!

so only ammonium compounds react with alkali to give ammonia!!!

And that's why answer is D!!

I think now its clear!!!
 
H

hassam

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aliya_zad said:
can someone help me with the 16th question..
http://www.xtremepapers.me/CIE/International A And AS Level/9701 - Chemistry/9701_w05_qp_1.pdf
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well....u shud first off all recognise there is a carbonate....and salt must be a double carbonate cos it produced effervescence later on adding to acid.....it ll be C not D..LET me tell u wats the tricky part....actually if we heat D both MgCO3 and CaCO3 WILL Decompose....but in C only one will decompose during heating as other one is very much stable so when acid is added it will react to produce CO2 again seen as effervescence
 
aliya_zad

aliya_zad

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i think its coz when, aluminium reacts with oxygen it forms a layer of aluminium oxide which prevents further reaction so how can it form a nitrate???
This is my kind of analysis....
 
workinghard

workinghard

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hv u seen da trend dat wenevr a nitrate or carbonate decomposes or reacts only the oxides remain da rest leave as gas...
i blv here da same theory applies... its C rite?!
u c wen u say D is da ans u r just changin metals ... doh N2 is being produced but so is AL(NO3)3 which is not justified
true dis is not decomposition in true sense but still i dnt think dat v can jst switch meatals...
besides if ma wild imagination 2 work i d say y shd AL replace BA in nitrate wen Ba is more reactive of the two...
so dats how i think n it eliminates D
den 4 B its almost da same thing cux ba nitrate hx not completely reacted n this compound is remainin Ba(NO2)2 besides O2 can also not be described as unreactive!!
i didnt evn check 4 homogenity i m dat careless:/
and in A NO is produced which is not unreactive........
i really am not good at xplaining doh.. sorry !
still hope u got it!!!!
 
X

Xthegreat

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because the definition of enthalpy change of formation is

'1 MOLE of compound is formed from its constituent element'

u have to divide the enthalpy of ICl by 2. so that you get 1 mole which would give u an enthalpy of 7kJmol instead of 14kJmole
 
alisha

alisha

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ambitious1 said:
That'll only happen if the graph plotted was of the concentration of reactants against time, not the rate of reaction against time.
Understood? =)
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got it! thanx!
 
X

xHazeMx

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the equation is,
2 H2O2 --------> 2 H2O + O2

A is wrong because adding water would result in an increase in the backward reaction so the volume of oxygen will decrease.
B is wrong because adding more H2O2 would make the curve more steep ! ( gradient increases ) but the graph is showing the opposite
C is wrong because the amount of catalyst used has no effect on the rate of reaction but in the graph there is an increase in the volume of the oxygen librated
D is the correct answer as temperature decreases, rate of the endothermic reaction decreases ( decomposition ), hence the curve's steepness decrease .. it is commonly known that as temperature decrease in an endothermic reaction the rate of reaction decreases but the yield of the products increases so D is the right answer

i hope everything is clear now :)
 
A

Anonymousx3

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xHazeMx said:
the equation is,
2 H2O2 --------> 2 H2O + O2

A is wrong because adding water would result in an increase in the backward reaction so the volume of oxygen will decrease.
B is wrong because adding more H2O2 would make the curve more steep ! ( gradient increases ) but the graph is showing the opposite
C is wrong because the amount of catalyst used has no effect on the rate of reaction but in the graph there is an increase in the volume of the oxygen librated
D is the correct answer as temperature decreases, rate of the endothermic reaction decreases ( decomposition ), hence the curve's steepness decrease .. it is commonly known that as temperature decrease in an endothermic reaction the rate of reaction decreases but the yield of the products increases so D is the right answer

i hope everything is clear now :)
Click to expand...

Isn't the answer B?
The answer for May/June 2007 question 11, according to the mark scheme, is B.
 
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