Chemistry: Post your doubts here!

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_12.pdf
q10 plz!

 

[Suchal Riaz]

Could u translate it to english plz

the beating stick of examination hall. it makes sense in urdu but looks dumb in english.

 

[ZaqZainab]

there is something we call in desi language as "examination hall ka danda". when it hits you head it makes you do extraordinary things in little time.

Never happen to me

 

[AbbbbY]

because you are super dumb
just kidding

Thanks, but maybe if I played less FIFA and tried studying in these 20 days I wouldn't have had such a problem

 

[GCE As and a level]

truth
proof:
View attachment 44981

I believe u but i was JK
Man BTW do u know how they calculate the mark {IT should be out of 140 not 130_
ANY WAY I am really THANKFUL TO U

 

[ZaqZainab]

I don't think there is any hospital offering brain transplant. if there was i would be happy to donate 0.0000000001% to others which will be sufficient to make those lucky few people superhuman.

How do you do it
Like i see you as a person who always studies and i can never do that i study for an hour take a break for like 3 hours

 

[GCE As and a level]

Thanks, but maybe if I played less FIFA and tried studying in these 20 days I wouldn't have had such a problem

PLZ SAY WE** NOT I

 

[Suchal Riaz]

Never happen to me

in the paper 1 on pst we had to do three set of question each set had one 4 marks, on 7 marks and one 14 marks question.
it took me half hour to do one 14 marks question only. the paper was of 1.5 hours. this way i couldn't complete even 70% paper in time.
but in examination hall my fingers raced so much that i completed paper 10 minutes earlier.

 

[GCE As and a level]

How do you do it
Like i see you as a person who always studies and i can never do that i study for an hour take a break for like 3 hours

Same here

 

[ZaqZainab]

in the paper 1 on pst we had to do three set of question each set had one 4 marks, on 7 marks and one 14 marks question.
it took me half hour to do one 14 marks question only. the paper was of 1.5 hours. this way i couldn't complete even 70% paper in time.
but in examination hall my fingers raced so much that i completed paper 10 minutes earlier.

Woh thats cool
but its vise versa for me
I can comple a P1 in 40 minutes at home but 'Bio pape 1' took me 1 hour and still didnt get time to check i have got problem with nervousness in exam hall

 

[Suchal Riaz]

just to clarify I DON'T STUDY ALL THE TIME
i study about 2-3 hours now. and started studies 5 days ago. i just pretend to study all times to encourage my friends to study and to try to hide my intelligence as i need to behave ordinary among ordinary people to look ordinary.

 

[Suchal Riaz]

Woh thats cool
but its vise versa for me
I can comple a P1 in 40 minutes at home but 'Bio pape 1' took me 1 hour and still didnt get time to check i have got problem with nervousness in exam hall

i was talking about paper1 of PST not mcq papers. btw i when i started it took me more than 2 hours to do one paper1 of chemistry as i had to make a lot of diagrams of organic chemistry, write all the equations, do all the working. now with expeience it all takes place in head and only minute working has to be done on paper. now it takes 40 sec to complete an average question but if i am stuck i can take about 2 minutes to find the solution. practices makes a man(and women) perfect.

 

[ZaqZainab]

just to clarify I DON'T STUDY ALL THE TIME
i study about 2-3 hours now. and started studies 5 days ago. i just pretend to study all times to encourage my friends to study and to try to hide my intelligence as i need to behave ordinary among ordinary people to look ordinary.

Every one is ordinary its you who make your self different
I am ordinary but i am the one who made myself study less and so i am less intelligent "
you decide what you wanna become and you made it to intelligence while i here am too lazy to do so

 

[ZaqZainab]

i was talking about paper1 of PST not mcq papers. btw i when i started it took me more than 2 hours to do one paper1 of chemistry as i had to make a lot of diagrams of organic chemistry, write all the equations, do all the working. now with expeience it all takes place in head and only minute working has to be done on paper. now it takes 40 sec to complete an average question but if i am stuck i can take about 2 minutes to find the solution. practices makes a man(and women) perfect.

when did you start like 5 days ago?
I started My first proper paper 20 days ago

 

[Suchal Riaz]

Every one is ordinary its you who make your self different
I am ordinary but i am the one who made myself study less and so i am less intelligent "
you decide what you wanna become and you made it to intelligence while i here am too lazy to do so

if one person is good at something than other then he must be worst at other things than the others.
if i am good at something(actually everything other than sports) it means you people are better than me in other things.

 

[Suchal Riaz]

 

[randomcod]

please pelase make it a bit more specific.
I though enthalpy change = enthalpy change of products - enthalpy change of reactants?

 

[..sacrifice4Revenge..]

any tips for the last 10mcqs?

 

[..sacrifice4Revenge..]

please pelase make it a bit more specific.
I though enthalpy change = enthalpy change of products - enthalpy change of reactants?

for combustion data, its reactants-products

for formation, products-reactants

bond energy, Exo+Endo

 

[Zepudee]

s08qp1

Q6.
H2O(s) --> H2O(g)

Moles of H2O = mass of ice/Mr of H2O = 1/18= 0.0556

PV/nT (ideal gas) = PV/nT (H2O)
(1)(24)/(1)(298) = (1)V/(0.0556)(596)

V = 2.67 dm^3

Q26.
Increase in the 2 oxygen means that the 2 OH has been oxidized to 2 COOH groups.
The two OH must be primary alcohols. Since is an unbranched butanol, the OH groups are on carbon 1 and 4.

Q27.
Use the 4 options and trial and error.

Before dehydration, the C=C bonds were actually CH-COH.

Check which of the 4 could possibly give us a tertiary alcohol (resistant to oxidation) before dehydration.
View attachment 44341
In this case, it was D.

Thank you