Biology; Chemistry; Physics: Post your doubts here!

[***amd***]

wohee na

kiya wohi? .-.

 

[***amd***]

taamba (copper) reacts with air? :O

answer this plz .-.

 

[Awesome12]

answer this plz .-.

Yes it does

 

[Faizan Muhammmad]

answer this plz .-.

not until heated

 

[Uchiha-Sasuke]

answer this plz .-.

on heating externally, yes otherwise not ... on heating it becomes CuO (black)

This is a very important question of Chemistry 5070_w13qp_11 question 14.
Why does the acid become more concentrated as dilute H2SO4 is being electrolysed?
The answer is A
View attachment 43240

H+ ions move towards cathode (H2)
OH- ions move towards anode (O2)
what gets left in solution is SO4-
(OH- H+ .. think of them as water) water is reduced in solution which will make it concentrated

 

[peacce]

English tomorrow??

yep.. agr summary mei word limit exceed hjai tu kia hta man i exceeded ittttttttttttttttt

 

[***amd***]

yep.. agr summary mei word limit exceed hjai tu kia hta man i exceeded ittttttttttttttttt

they'll cut off the extra words and then read it.
how much did u exceed?

 

[Ram97]

yep.. agr summary mei word limit exceed hjai tu kia hta man i exceeded ittttttttttttttttt

If u see the ms it says marks are given for OWN WORDS and USE OF LANGUAGE. I dont think marks would be deducted.
I forgot to write no.of words but it was under the limit

 

[Uchiha-Sasuke]

Hey guys, so I found this weird thing today that kinda contradicts what we've studied .. or atleast what Iv'e studied ..
We all know the test of No3- ions .. actually it's quite simple ...dil NaOH , Al powder +heat = NH3 .. that's fine but I've compiled this contradiction of CIE.
check this : B8 Q ci)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s06_qp_2.pdf
MS : http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s06_ms_2.pdf
it says NaOH in either part ok ?
now check this one : A6 e)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s09_qp_2.pdf
MS : http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s09_ms_2.pdf
It emphasized for the first time (Excess).... okay no prob .. we've been doing this in p4 for a long time...
^those above were just to confirm it ..
now look at this: B7 d ii)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_qp_21.pdf
MS http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_ms_21.pdf
for the first time now it says (CONCENTRATED) whaaaaaaat ?

Is it just me or are the situations changing on every question ?
can someone please clear up what kind of NaOH to use -_-
#GettingRealTiredOfYourShitChemistry

 

[Awesome12]

Hey guys, so I found this weird thing today that kinda contradicts what we've studied .. or atleast what Iv'e studied ..
We all know the test of No3- ions .. actually it's quite simple ...dil NaOH , Al powder +heat = NH3 .. that's fine but I've compiled this contradiction of CIE.
check this : B8 Q ci)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s06_qp_2.pdf
MS : http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s06_ms_2.pdf
it says NaOH in either part ok ?
now check this one : A6 e)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s09_qp_2.pdf
MS : http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s09_ms_2.pdf
It emphasized for the first time (Excess).... okay no prob .. we've been doing this in p4 for a long time...
^those above were just to confirm it ..
now look at this: B7 d ii)
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_qp_21.pdf
MS http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w12_ms_21.pdf
for the first time now it says (CONCENTRATED) whaaaaaaat ?

Is it just me or are the situations changing on every question ?
can someone please clear up what kind of NaOH to use -_-
#GettingRealTiredOfYourShitChemistry

Ok just calm down. Both the excess and concentrated are written in brackets. So it is not compuslory to include them. You can however include them, and they will get accepted. So as you can see CIE is actually accepting more responses

Your answer is absolutely correct. Just include that the gas produced turn litmus blue, and that it is ammonia

 

[Uchiha-Sasuke]

Ok just calm down. Both the excess and concentrated are written in brackets. So it is not compuslory to include them. You can however include them, and they will get accepted. So as you can see CIE is actually accepting more responses

Your answer is absolutely correct. Just include that the gas produced turn litmus blue, and that it is ammonia

wasn't accepting more responses used to be in ALLOW: .... or IGNORE: .... ?

 

[Awesome12]

wasn't accepting more responses used to be in ALLOW: .... or IGNORE: .... ?

Yes it is. I just couldn't find any other way to put this

 

[Uchiha-Sasuke]

Yes it is. I just couldn't find any other way to put this

smooth move sherlock... >>

 

[DaniyalK]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_w11_qp_11.pdf
Why is the answer to 3 c?

 

[asadalam]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w11_qp_11.pdf
Why is the answer to 3 c?

Nitrogen comprises 79% of air present,so naturally some would be present in the tubes before the experiment,

 

[M.Omar]

wasn't accepting more responses used to be in ALLOW: .... or IGNORE: .... ?

both cases consider more pts..It,s just tht ALLOW box includes some unusual but correct answers or slightly vague but it still understandably correct..
Brackets as he said provide optional responses or additional...at least I am sure abt this..No need for brackets if pts r compulsory and in such questions they wud underline keywords if they did matter

 

[kirann]

does ammonium chloride react with dilute sulphuric acid?

 

[afrolina]

Anyone wants to discuss english??

 

[Awesome12]

Hey guys check this out
http://wiki.answers.com/Q/How_do_you_test_a_liquid_for_alcohol?#slide=2

 

[asadalam]

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This is olevel thread not IGCSE .-.