Biology; Chemistry; Physics: Post your doubts here!

[SomeStudent]

If the percentages are coming

Ca50/12 X20/6

that becomes

Ca4.2 X3.33

then divide both with 3.33

Ca4.2/3.3 X3.33/3.33

Ca1.26X1

which becomes

CaX

righty! thanks!

 

[bogus]

ywr is mein confusion kia ha 1st few tubes r rejected coz the nitrogen in air results in contamination...simple

so where does nitrogen go after that???

 

[ashiqbal]

zomg .. what are their formulae ? and states?

I think the answer will be .. Al2OH + NaO .. as when we dissolve in water H+ and OH- will also take part in the reaction!!

Na2Al2O4 is formed. <-- Google

Not in our course as Sodium Aluminate will be formed !! and its a complex salt ... !!

i read in a past paper once!!!! around 2006 till 2008. So yeah, it is in our syllabus, and i lost a mark solving that.

 

[SomeStudent]

4.65 ...dnt round off till the end !

yup, that!! Thanks

 

[syed1995]

i read in a past paper once!!!! around 2006 till 2008. So yeah, it is in our syllabus, and i lost a mark solving that.

Complex Salts hamaray syllabus mein nai hain .. yaar question dhoondh day .. bhai hoga dono mill kay solve karein gay then =D

 

[syed1995]

so where does nitrogen go after that???

Good question .. anyone here to answer it?

 

[ashiqbal]

http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_s10_qp_11.pdf

Q14..

increase the temperature. that will favour backward reaction

 

[syed1995]

mein chala ab thora parhnay yahan betha raha tu past paper kon karega =PP

 

[MustafaMotani]

why not B?

q k red ink mein ek extra unnecessary spot hai

 

[SomeStudent]

4.65 ...dnt round off till the end !

YUP! was asking this! Thanks

 

[bogus]

Guys... I canr remember which mcq paper it was but there was this paper where a reaction occurs (decomposition of H2O2 i guess) where the first few test tubes were rejected because they contain nitrogen. Can u explain it to me and potst the question if u can find it? Thanks in advance

ashiqbal help!! where does nitrogen go...i mean it came from air but why were first Few rejected air to disappear nahin hoti???

 

[a.abid]

q k red ink mein ek extra unnecessary spot hai

NAHIn actually the dots arent in line

 

[Mayedah]

YUP! was asking this! Thanks

Np

 

[ashiqbal]

Complex Salts hamaray syllabus mein nai hain .. yaar question dhoondh day .. bhai hoga dono mill kay solve karein gay then =D

w11_qp21 Q8 (a)(ii)
http://www.xtremepapers.com/papers/...l O Level/Chemistry (5070)/5070_w11_qp_21.pdf
ab rona mat kai yeh kahan sai aa gaya! i tod you so!

 

[MustafaMotani]

increase the temperature. that will favour backward reaction

ye kis ka anser hai ..:/

 

[syed1995]

increase the temperature. that will favour backward reaction

what question were you answering ??

And now that we are on the topic ..

N2(g) + H2(g) <--> NH3(g)

If forward reaction is exothermic ..

then decreasing the temperature and increasing the pressure will make more Ammonia ...?

I haven't grasped the concept behind applying pressure on gases, where to decrease and where to increase .. can ya help me out there??

 

[MustafaMotani]

NAHIn actually the dots arent in line

Hoga ab mein phir se not dhoondhing.. :

 

[Mayedah]

ashiqbal help!! where does nitrogen go...i mean it came from air but why were first Few rejected air to disappear nahin hoti???

The first test tubes were rejected because it had nitrogen and so those test tubes went used ...they have to remove nitrogen by some how and thn do the experiment !

 

[syed1995]

w11_qp21 Q8 (a)(ii)
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_w11_qp_21.pdf
ab rona mat kai yeh kahan sai aa gaya! i tod you so!

Answer tu question mein diya hua hai aur mjh say pooch rahay ho .. :\

"The products of the reaction are aqueous sodium aluminate, NaAlO2, and water."

 

[multixamza01]

ashiqbal help!! where does nitrogen go...i mean it came from air but why were first Few rejected air to disappear nahin hoti???

We release it into the air again . We need oxygen . Contaminations ko chor detay hai .