Chemistry: Post your doubts here!

[USMAN Sheikh]

in quesstion 12 ans should be B in it u have to use common sense as accross the group EN inc and Down the group it decreases !! so Be will be the answer asfrom Be to Al we are moving one step in fovour to inc EN and one step down in order to dec EN hence both will cancel each other !

 

[USMAN Sheikh]

In ques 17 find out epirical formula using percentage it will be values of empirical will be 1:1.5:1.5:10:7
in above eq Ca is 2 so we can do it by ratio method if ca is 1---------- 1.5 of AL so if Cais 2 ---------X
ie al=X=3 si will also be three similar rations C is your ans

 

[USMAN Sheikh]

Quickly need help !!!! how to do molar calcu lation in 1st question of titration the value of titre is 43.75 !!! need help with full details !!

 

[xhizors]

In question no 7 use hess law !! the equation build by using hess law will be -940+X=2*(-110) it will be C +720!!

Thanks i forgot the fact of 2 mol


Thanks for other two answers aswell

 

[xhizors]

Q19
http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s11_qp_12.pdf
what is identical oxidation state ??

 

[Muhammad Talha]

Thanks smzimran and abcde.....

 

[smzimran]

Q19
http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s11_qp_12.pdf
what is identical oxidation state ??

Ans is A
H and Cl both have oxidation states +1 (Oxygen has -2)

Identical means same oxidation state of two different elements in a single compound

 

[saudha]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_w10_qp_12.pdf

q2 why is the answer b?can any1 tell me the concept pls?

 

[Sky Capri]

OCT/NOV 2011, P11, Question 8, about the dissolving of sulfur dioxide in water. Why is the answer A?

 

[Sky Capri]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_w10_qp_12.pdf
q2 why is the answer b?can any1 tell me the concept pls?

When the temp. rises, the average kinetic energy of the molecules also increases. So the peak of the graph shifts to the right.

 

[saudha]

OCT/NOV 2011, P11, Question 8, about the dissolving of sulfur dioxide in water. Why is the answer A?

i think bcoz according to the bronsted-lowry theory bases are proton acceptors and here it is right ... if u feel any other option correct...u can put tht doubt forward too.!

 

[saudha]

When the temp. rises, the average kinetic energy of the molecules also increases. So the peak of the graph shifts to the right.

thxx

 

[omg]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_w03_qp_4.pdf

pls smbdy explainn Q4. part c to mee!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[saudha]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s02_qp_1.pdf
pls explain hw do u get D for q2??!!

 

[ad98ify]

kindly make a separate topic for A2!
it takes alot of time to scan through the whole page to find questions only for A2 as here majority of the people are asking AS questions

 

[smzimran]

kindly make a separate topic for A2!
it takes alot of time to scan through the whole page to find questions only for A2 as here majority of the people are asking AS questions

Correct! I agree

 

[ad98ify]

can anyone answer it? please? A2 students?

 

[z.muhammadhusayn]

i need help....the cie exams are cuming up in may-june and i still have nowhere to find the other variants of the chem pprs for revision, can anyone help?? i would appreciate....
thanks alot,
and god bless us all to be successful in our lives!!!
"whoever asks questions, will gain knowledge"
"god raises among you the believers and those with knowledge in high degrees" (57:11)

"genius is seeing what everyone has seen and thinking what NO ONE HAS THOUGHT" -ALBERT SZENT-GYORGI(discoverer of vitamin c)

 

[smzimran]

http://www.xtremepapers.com/CIE/International A And AS Level/9701 - Chemistry/9701_s02_qp_1.pdf
pls explain hw do u get D for q2??!!

A very simple question:
Empirical formula mass = 30

No, of moles of carbohydrate = 1.8/30 = 0.06
The equation is:
(CH2O)n + (3n/2) O2 --> nCO2 + nH2O
So molar ratio of carbohydrate to CO2 is 1:1
It means No. of moles of CO2 = 0.06
mass of CO2 = 0.06 * 44 = 2.64
Thats why it is D

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[saudha]

A very simple question:
Empirical formula mass = 30

No, of moles of carbohydrate = 1.8/30 = 0.06
The equation is:
(CH2O)n + (3n/2) O2 --> nCO2 + nH2O
So molar ratio of carbohydrate to CO2 is 1:1
It means No. of moles of CO2 = 0.06
mass of CO2 = 0.06 * 44 = 2.64
Thats why it is D

​

thankyou