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Chemistry: Post your doubts here!

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Mohammed salik

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Haya Ahmed said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J _2006_P1 -- Q32

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!! :cry::cry::confused:
Click to expand...
M/J _2006_P1 -- Q32
Ans Is B.
1. It says enthalpy change of atomisation, yes we need to Know because Na(s) is converted to Na(g)
2. says Ionisation energy, we need Ionisation energy because it is converted from Na(g)(neutral) to Na(g)(Positive ione)
3. We dont need it because formation if for compounds not elements! So only 1 and 2!!
Hope I Helped!! :)
 
papajohn

papajohn

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Haya Ahmed said:
Q12 pic can you upload it again because file not found and for Q9 the question is asking about which will release the greatest energy so how did we skip the A, B, C options as they have H-C and C=O bonds which have more enery than those C-H bonds in option B !! I didn't get it
Click to expand...
Alkanes are fuel .
 
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Mohammed salik

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Haya Ahmed said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39

M/J_2011_P12 -- Q8

O/N_2011_P12 -- Q26

O/N_2009_P12 -- Q10 , Q20, Q28

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!! :cry::cry::confused:
Click to expand...
O/N_2011_P12 -- Q26
Ethanol is converted to Ehanal (aldehyde)
First find moles of ethanol :-
Moles=mass/Mr
Mass=2.3g..... Mr=46 (C2H5OH)
Moles=0.05
Now find mass of aldehyde:-
Mass=mole * Mr
Mole=0.05...... Mr=44(C2H4O)
Mass=2.2g
But question says yeild is 70%
so 70/100 * 2.2 =1.54 which Is A!!
Hope I Helped! :)
 
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Mohammed salik

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Haya Ahmed said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40

M/J_2012_P12 -- Q5 , Q28 , Q36

Please someone help me I'm dying here from confusion !!! :cry::cry::confused:
Click to expand...
M/J_2012_P12 -- Q5 , Q28 , Q36
Q5:-(A) Iodine because it has covalent bonds (I2) and vanderwaals forces!
Q36:-(D)Because haber process is N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ·mol−1)
so Forward reaction is exothermic, if u Increase temp yeild goes Down, but Rate increases because Particles gain K.e. So 1 is Correct!
2 says High Pressure decreases yeild, thats wrong because High pressure favours side with less moles which is forward , this would increase yeild.
If 2 is Wrong then option is D! (no need to look at 3)
 
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Mohammed salik

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Haya Ahmed said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40

M/J_2012_P12 -- Q28

Please someone help me I'm dying here from confusion !!! :cry::cry::confused:
Click to expand...
O/N_2009_P12 -- Q10 , Q20, Q28, Q34, Q38 , Q40
Q40:- (C) 1. it says one monomer would form polymer? how is that posible? so 1 is wrong then automatically answer is C.
Q38:-C ,Ethanol is oxidized by KMnO4 Not Alumina. so 1 is wrong. then automatically answer is C.
;)
 
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Mohammed salik

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Haya Ahmed said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39

O/N_2009_P12 -- Q10 , Q20

M/J_2012_P12 -- Q28

Please someone help me I'm dying here from confusion !!! :cry::cry::confused:
Click to expand...
O/N_2004_P1 -- Q9, Q12, Q13, Q39
Q9:-(B) Because it is alkane and alkanes produce max energy! i think u could also do this in terms of bond energy which is time consuming ;)
Q12:-(B)https://www.xtremepapers.com/community/attachments/upload_2014-4-25_12-27-47-png.40167/
Q13:-(D) Because it should be With an alkali which is NaOH. (MgOH is Insoluble!)
Q39:-(D) This cant be dehydrated because the Carbon next to CH3OH has No Hydrogens so it cant be dehydrated. so 2 is Worng.
Then Ans is D!!
 
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aaaamfa

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Mohammed salik said:
I will start with D
First write down the equation:-
........................ 2P ------ Q + 2R
Initial Moles= 2 (P) 0(Q) 0(R)
It is given in the question x moles of R at Equilibrium, so we could find moles of Q using Mole ratio.For P since P:R is 2:2=1:1 Then P would be Initial moles - the moles of R at Equilibrium.
Equil Moles= (2-x )(P) ( x/2 ) (Q) ( x)(R)
Total (Add them up) = 2-x+(x/2)+x = (2+x/2) so the ans is D
If u Need further explaination Do tell Me!
Hope i helped! :)
Click to expand...


What a brilliant explanation i have been trying to figure this out since 2 days
Great explanation (y)
 
Haya Ahmed

Haya Ahmed

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Mohammed salik said:
O/N_2004_P1 -- Q9, Q12, Q13, Q39
Q9:-(B) Because it is alkane and alkanes produce max energy! i think u could also do this in terms of bond energy which is time consuming ;)
Q12:-(B)https://www.xtremepapers.com/community/attachments/upload_2014-4-25_12-27-47-png.40167/
Q13:-(D) Because it should be With an alkali which is NaOH. (MgOH is Insoluble!)
Q39:-(D) This cant be dehydrated because the Carbon next to CH3OH has No Hydrogens so it cant be dehydrated. so 2 is Worng.
Then Ans is D!!
Click to expand...
for question 9 it is not possible by bond energy thingy and for Q12 isn't the graph supposed to be shifted to right ? and for Q13 why Al2O3 not possible ?!
 
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