CHEM AND BIO HELP AND TIPS HERE

[rameeziiii]

umm...no more questions?

[Vin]

i have urgent question in 2004 may june q 4 b iii i dnt get it at all and same paper 7 b (ii) in ms they rounded the 0.125 to 0.1  suppose it waz cuz they gave masses to 1 decimal why they didnt do the same in c (i) and (ii)

^^ I'm sorry to say I'm too bored solving this ques. Plus I'm done with chem so I don't really feel like doing it now jk

[Shazizzzle]

Was the paper easy?

[Lariemeeva]

http://freeexampapers.com/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
Q5b.
I'm completely confused, and it obviously has something to do with stiochiometery which I'm really not good at. Anyone can help?

[Raywin]

http://freeexampapers.com/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
Q5b.
I'm completely confused, and it obviously has something to do with stiochiometery which I'm really not good at. Anyone can help?

This has been discussed a lot before.. BUT, here it is :

"the vol. of phosphate soln used in cm3 is half the height of the ppt in mm
also at 8cm3 all the soln is used up. tht is because adding more does not increase the height of the ppt meaning there was no further reaction on adding more.
also the formula is T3(PO4)2-----because

u take it as 12cm3 of T nitrate react with 8cm3 of sodium phosphate (thts wen all the reactants r used up)
so.....12:8...simplify it
12:8
6:4
3:2
and therefore u get T3(PO4)2"

courtesy : mohit

[Baladya]

http://www.freeexampapers.us/IGCSE/Chemistry/CIE/2008%20Nov/0620_w08_qp_03.pdf

yoyo Can anyone explain 4)b)ii)  how is it possible that the mole ratio in mark scheme is 6:6 (1:1) when the percentage of carbon is 92.3 and Hydrogen is 7.7??

Thanks

[Raywin]

Guys, heres a Q that has been bothering me. :/ Does pollution affect the no. of organisms or the no. of species within tht polluted area?
Thanks,

[Baladya]

Guys, heres a Q that has been bothering me. :/ Does pollution affect the no. of organisms or the no. of species within tht polluted area?
Thanks,

what do u exactly mean.... with  in that polluted area is right... but what do u mean with 'no. of organism' (without anything)

[Raywin]

what do u exactly mean.... with  in that polluted area is right... but what do u mean with 'no. of organism' (without anything)

Hmm, like in a polluted area, does the pollution affect the number of organisms like for eg: due to pollution the no. of organisms reduced from 1000 to like 400, umm get it? Organisms like the total ones not looking at species here but general. and the other condition is does species reduce, for eg, the no. of species reduced from 10 to like 5. :/   

[Vin]

Hmm, like in a polluted area, does the pollution affect the number of organisms like for eg: due to pollution the no. of organisms reduced from 1000 to like 400, umm get it? Organisms like the total ones not looking at species here but general. and the other condition is does species reduce, for eg, the no. of species reduced from 10 to like 5. :/   

Hmm... I think I've solved this one somewhere.. which year?

[Raywin]

Hmm... I think I've solved this one somewhere.. which year?

I did it long time ago, but I havent found it yet, i forgot the paper :/ but ill check which one it is and get back yeah..

[Airhead]

How do you guys copy a question onto this forum using .png or whatever? idk how to.. lol

Well, anyway, can someone help me out with M/J 2007 Q18?

I think it's D. If humidity is low, the plant loses water. And if the light intensity is also low, the plant can't photosynthesize.

[Vin]

easy, its C ofc. Temperature (by light intensity) increases, transpiration rate increases. Humidity low (less water mol. in amt. so water diffuses out)

[Raywin]

It's not, it's C. idk why, I picked D too.

And this is all the examiner report says: "This proved to be one of the more difficult questions on the paper, though it was noticeable that it was the able candidates who reasoned their ways to the correct response. Evident errors were shown by over a third of the candidates who thought that high humidity would cause wilting, and by well over half of them that thought low light intensity might be responsible for the condition."

Anyone solved this before and know why it's C? Thanks

See, humidity means a lot of water vapor is in the air around the plant. So, this reduces transpiration see? so thus, it will NOT wilt as transpiration is reduce. High light intensity will INCREASE transpiration. This could cause wilting as the plant might not be able to get as much water that is being lost to transpiration. Thus, the ans is C.

[Raywin]

Thank you to Raywin and Vin for taking the time to answer.

But yeah if humidity is reduced, transpiration is increased, I got that.
BUT if light intensity is LOW, doesn't that mean the plant won't be able to photosynthesize, which means it will wilt? Which means D could be right too?

OR ohhhh wait, low light intensity = low sunlight = low photosynthesis = plant turns YELLOW, it doesn't necessarily have to wilt, right?
So does that mean that ONLY a decrease in water causes wilting?

YES, photosynthesis will not make the plant wilt, its the water that flows through the stems that decide if the plant is wilting or not.