Chemistry: Post your doubts here!

[Xialay Khan]

sory me have no idea

no problem ?? any one else ?

 

[user]

no problem ?? any one else ?

this is the A levels thread..
u can check in the o levels section...they'll be able to help u

 

[Xialay Khan]

where do u get the solved pastpapers from ?

 

[RGBM211]

Use of the Data Booklet is relevant to this question.
560 kg of nitrogen and 120 kg of hydrogen are pressurised, heated and passed over an iron
catalyst. When the mixture of gases reaches equilibrium, it contains 96 kg of hydrogen.

Which mass of ammonia does it contain?
A 24 kg B 68 kg C 136 kg D 680 kg

answer is C

Can someone please explain me how to solve this question and yea mmm whats the difference between induce dipole and permanent dipole

 

[geek101]

because they didn't just say the no of electrons in the outer shell, right? t
hey meants the total no of electrons in the whole ion eh?

yes

 

[toxicdevil]

For those who gave the paper today. what was the answer of organic mcq. where they asked about compund X??

 

[MysteRyGiRl]

^whoaah ur not alowed 2 discus it here there r still ppl going 4 da pprs

 

[Most_UniQue]

Chem was really easy!!!! Easier than what I expected

 

[MysteRyGiRl]

^relief

 

[saudha]

well done with my xam...and i feel good .............

 

[RGBM211]

someone please solve this

Use of the Data Booklet is relevant to this question.
560 kg of nitrogen and 120 kg of hydrogen are pressurised, heated and passed over an iron
catalyst. When the mixture of gases reaches equilibrium, it contains 96 kg of hydrogen.

Which mass of ammonia does it contain?
A 24 kg B 68 kg C 136 kg D 680 kg

answer is C

Can someone please explain me how to solve this question and yea mmm whats the difference between induce dipole and permanent dipole

 

[RGBM211]

^have exams in few hrs please anyone

 

[MysteRyGiRl]

Which factor helps to explain why the first ionisation energies of the Group I elements decrease
from lithium to sodium to potassium to rubidium?
A The nuclear charge of the elements increases
B the outer electron is in the s subshell
C repulsion between spin paired electrons increases
D shieldng efect of inner electrons increases
answer is D bt shouldnt it b C???

 

[MysteRyGiRl]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s09_qp_1.pdf
ques no 1, 2,28,40 plzzz

anyone here who can help??

 

[smzimran]

someone please solve this

Use of the Data Booklet is relevant to this question.
560 kg of nitrogen and 120 kg of hydrogen are pressurised, heated and passed over an iron
catalyst. When the mixture of gases reaches equilibrium, it contains 96 kg of hydrogen.

Which mass of ammonia does it contain?
A 24 kg B 68 kg C 136 kg D 680 kg

answer is C

Can someone please explain me how to solve this question and yea mmm whats the difference between induce dipole and permanent dipole

96 kg hydrogen is left means (120 - 96) = 24 kg was used up

The equation:
3H2 + N2 --> 2NH3

(3 * 2) = 6 kg hydrogen produces (2 * 17) = 34 kg ammonia

1 kg hydrogen would produce (34/6) kg ammonia
24 kg hydrogen would produce
= (34 / 6) * 24
= 136 kg ammonia

That is why answer is C

 

[busy bee]

http://www.chemguide.co.uk/inorganic/group2/thermstab.html hope this helps with the thermal stabilities of group 2 nitrates & carbonates

 

[Akshaya bhattarai]

Thank you very much!

how was your exam buddy?

 

[busy bee]

anyone here who can help??

for question 40 :
the last option is incorrect so it has to be 1 & 2
2 because a salt is formed and 1 because alcohol is formed with the (OH) from (NAOH)
for question 28 :X contains nine carbon atoms and reacts with 2,4-dinitrophenylhydrazine reagent.
3 DNP are required to react with 9 carbon atoms

 

[MysteRyGiRl]

for question 40 :
the last option is incorrect so it has to be 1 & 2
2 because a salt is formed and 1 because alcohol is formed with the (OH) from (NAOH)
for question 28 :X contains nine carbon atoms and reacts with 2,4-dinitrophenylhydrazine reagent.
3 DNP are required to react with 9 carbon atoms

yes but why 3?can u plz explain?

 

[msohiabch]

For those who gave the paper today. what was the answer of organic mcq. where they asked about compund X??

it was C the alcohol