Last minute preparation on MCQS 9701 and 9702. Discussion here.

[saturn21]

Methane is the simplest alkane, by default it releases the lowest amount of carbon dioxide.

Okey..but what about methanol?

 

[The Sarcastic Retard]

Okey..but what about methanol?

I am not able to see the pic... Can u again post the pic or a question paper link ??

 

[saturn21]

I am not able to see the pic... Can u again post the pic or a question paper link ??

May/june 2014 var 13 question 24

 

[The Sarcastic Retard]

May/june 2014 var 13 question 24

View attachment 57477


Ans is B..how?

Energy need for all is same.
Hence, Energy = 1 * 4.18 * 80 = 33.4KJ/Mol
For option B moles will be less.
33.4 ---> 1mol
890 --> lesser than other options.

 

[shahzaib9291]

 

[The Sarcastic Retard]

View attachment 57484

Total volume = 50cm^3
Energy = 50 * 4.18 * 2.5 J = -522.5J/mol (temp rise hence exothermic)
0.0025mol --> -522.5J
1mol ---> -209kj/mol

 

[DarkEclipse]

Hows physucks going on??

Mediocre. Chem is going better

 

[phanttasy]

Need help on question 9 in 2007 ON variant 1

 

[The Sarcastic Retard]

Need help on question 9 in 2007 ON variant 1

Physics or chemistry?

 

[The Sarcastic Retard]

View attachment 57491

Use H = m * c * delta T
m = 100g
c = 4.18
delta T = 33C
Answer will be B

 

[phanttasy]

Physics or chemistry?

sorry! it is chemistry

 

[The Sarcastic Retard]

sorry! it is chemistry

moles of SO3 2- : moles of electrons : moles of metal
0.0025 : ? : 0. 005
1 :? : 2
1 : 2 : 2

2 mol of metal gained 2 mol of electrons
1 mol of metal gained 1 mol of electron (oxidation state will thus decrease by 1)
Original oxidation state of metal = +3
Final oxidation state = +3 - 1 = +2
-Metanoia

 

[saturn21]

Energy need for all is same.
Hence, Energy = 1 * 4.18 * 80 = 33.4KJ/Mol
For option B moles will be less.
33.4 ---> 1mol
890 --> lesser than other options.

I still don't get it..but thanks for helping

 

[phanttasy]

moles of SO3 2- : moles of electrons : moles of metal
0.0025 : ? : 0. 005
1 :? : 2
1 : 2 : 2

2 mol of metal gained 2 mol of electrons
1 mol of metal gained 1 mol of electron (oxidation state will thus decrease by 1)
Original oxidation state of metal = +3
Final oxidation state = +3 - 1 = +2
-Metanoia

Thank you very much!

 

[The Sarcastic Retard]

I still don't get it..but thanks for helping

Energy needed for all is same right?

So that energy = -33.4KJ/mol
Try for every option in which do we get less number of moles of CO2
For B : (33.4/890) = 0.03
For C : (33.4/715) = 0.05

 

[saturn21]

Energy needed for all is same right?

So that energy = -33.4KJ/mol
Try for every option in which do we get less number of moles of CO2
For B : (33.4/890) = 0.03
For C : (33.4/715) = 0.05

Omg i get it now..thank youuuu

 

[The Sarcastic Retard]

Thank you very much!

 

[SadiaMaryam]

any tips to remember the organic reactions? anyone plz! ...I sometimes mix them up

 

[The Sarcastic Retard]

any tips to remember the organic reactions? anyone plz! ...I sometimes mix them up

Gokhapatiiiiiii!! Ratafication

 

[awesomaholic101]

any tips to remember the organic reactions? anyone plz! ...I sometimes mix them up

usually, i just list down all the reactions under each homologous series ... like actually write it down after studying them up WITHOUT looking into ur textbook. So it kinda registers in your brain in that order and you will be able to recall during ur exam, in shaa Allah. Look through it or list it in ur mind before going into exam maybe.

Gokhapatiiiiiii!! Ratafication

what?