Physics, Chemistry and Biology: Post your doubts here!

[Dani222]

Any tips for Physics Paper 3???
How to study? Past papers or go over the notes again?

 

[Mohammed Khaled]

when will the first chemistry paper 6 variant 1 end??

 

[always-smile :)]

do v need 2 noe test 4 alcohols?

my burning it if it produced flames it would be alcohol
hope i helped

 

[always-smile :)]

when will the first chemistry paper 6 variant 1 end??

its today at 3 pm btw in KSA it ends at 4
i don't knw about other places

 

[Ahmed Raouf]

CHEMISTRY: i need help in the compounds colors, i dont know anything about them and the paper 6 exam is in 4 hours so please ANYONE tell me some. thnx in advance

 

[za Shadow]

For O/N 2011 PAPER 62 you donot have to mention the step for concentration just write that calculate it
The other I am just going to answer nw ,i answered this question as I just solved it now.

For paper 63 just mention it is a carbonate ,and write metal no need to go in detail dude ,its transition or whatever,write a metal name okey ,transition was mentioned as Iron in it.

what do u mean by only write metal the ms said "non transition metal/named metal e.g. sodium (1)" ?????????

To question 6 paper 61 you have to reweigh it they have mentioned it there that means you can put on electric balance.

THANKS A LOOOOTT

Question 5 (e) = non transition , because solid E is calcium carbonate .. so calcium is NOT a transition metal ..
Question 6 = every markscheme since 2002 has this way of measuring the volume, so learn this its better
Question about concentration = its the same as the above

question 5 its not calcium how did u know??????

THANKSSSSSS VERRRRRRYYYY MUCHHHHH

 

[zaid1q]

chemistry: The most concentrated acid needs the most volume of solution to neutralise??? plz help

 

[Ahmed Raouf]

chemistry: The most concentrated acid needs the most volume of solution to neutralise??? plz help

YES IT DOES, titration is quantitative meaning that certain number of particles react with each other. Suppose you have two classrooms(acid) of the same size(same volume in experiment) you're going to give them apples(solution), the class that takes more apples(more solution) means that it contains more students(particles) so it is the more concentrated.
so yes, hope i explained it well.

 

[Ahmed Raouf]

CHEMISTRY: pls anyone tell me colored compounds and their colors

 

[Moostafa]

Hey guys, I would really appreciate if someone would look into the Physics Winter 2008 paper, question 6b) It asks for the angle of refraction which is obviously using the formula n=sin i/sin r BUT in the mark scheme it says use n=sin r/sin i OR n=sin i/sin r in any form and then it goes on to show the answer for sin r/sin i which makes no sense. Why have they used the formula the other way around?

 

[kainat husain]

every one gave their chemistry paper 6?

 

[lenin]

in the syllabus they wrote appericiate that massive particles may be moved by light what do they mean ??

 

[lenin]

Hey guys, I would really appreciate if someone would look into the Physics Winter 2008 paper, question 6b) It asks for the angle of refraction which is obviously using the formula n=sin i/sin r BUT in the mark scheme it says use n=sin r/sin i OR n=sin i/sin r in any form and then it goes on to show the answer for sin r/sin i which makes no sense. Why have they used the formula the other way around?

if they say refactive index in the glass use sin r/sin i if they said refractive index to air its sini /sin r

 

[Moostafa]

if they say refactive index in the glass use sin r/sin i if they said refractive index to air its sini /sin r

Thanks!

 

[kainat husain]

PLEASE PLEASE SOME ONE HELP URGENT
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w06_qp_3.pdf
q-1 b (iv)
q-5b
q-6a, c
q-7a
q-8a
q- 9 c how to draw :/
q-10 c
and 11 a
plz plz plz help plz

 

[Wasif`]

It was Easy, the last question answer was :-
1. Place each Corrosion inhibitor in 3 test tube of equal amount.
2. Take 3 steel nails and place them in 3 water bowl.
3. Place each inhibitor in bowl.
5. Leave it undisturbed for 3-4 days in presence of air.
6. After 4 days, Remove the rust which will be Flaky brown solid (FE2OH3.xH2O) and dry them and weigh each of them.
7. The one which has more weigh will be least effective corrosion inhibitor and one with lower weight will most effective corrosion inhibitor.

 

[Mohsin41]

todays chemistry paper 6 was great! question 5 answer was Copper Carbonate and gas was CO2

 

[za Shadow]

if they say refactive index in the glass use sin r/sin i if they said refractive index to air its sini /sin r

thanks that helped me 2

 

[za Shadow]

PLZ HEEEEELLPP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_qp_03.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_ms_3.pdf
q 1 d ii) my answer was 0.72 but it was wrong although i used speed=dist/time the correct answer was 0.36 WHYYYY plzzzzz help me
q 5 c) how do we get the answer????? plzzz tell me the steps

 

[Dani222]

PLZ HEEEEELLPP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_qp_03.pdf
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w08_ms_3.pdf
q 1 d ii) my answer was 0.72 but it was wrong although i used speed=dist/time the correct answer was 0.36 WHYYYY plzzzzz help me
q 5 c) how do we get the answer????? plzzz tell me the steps

q1d ii) distance= speed x time
= 1.2 x 0.6 = 0.72/2
= 0.36m
since the trolley moves backwards and forwards

q5 c) mass x Specific Heat Latent = Power x time
m x L = P x t
(16.3 - 2.1) x L = 40 x (2 x 60) time has to be in seconds
14.2 x L = 40 x 120 simplify to get L
L = 338 J/g