Physics, Chemistry and Biology: Post your doubts here!

[natsume hyuga]

when they ask for a straight line graph do u draw a line between each point using a ruler? cuz then sometimes it doesnt appear as a straight line but crooked instead.

 

[sma786]

when they ask for a straight line graph do u draw a line between each point using a ruler? cuz then sometimes it doesnt appear as a straight line but crooked instead.

It depends on graphs, and u shud never draw a graph with a ruler unless the gradient is constant ..

 

[Mohsin41]

any one have any problem in chemistry??? i will solve.

 

[sma786]

CHEMISTRY HELP
Hey, can anybody teach me how to draw structural formula's of polymers ?? please it is important =[

 

[Mohsin41]

CHEMISTRY HELP
Hey, can anybody teach me how to draw structural formula's of polymers ?? please it is important =[

there are types of polymers ( natural and condensation, synthetic )
Synthetic:
( polyethene, polychloroethene, are important)

e.g monomer of polyethene is simple ethene ( CH2=CH2 ) so extend it and remove the double covalant chain like this ( CH2-CH2...........so on depends on how much question demand )



Have a look at this ... hope it will help.

 

[Mohsin41]

will post more soon or give me ur email

 

[sma786]

there are types of polymers ( natural and condensation, synthetic )
Synthetic:
( polyethene, polychloroethene, are important)

e.g monomer of polyethene is simple ethene ( CH2=CH2 ) so extend it and remove the double covalant chain like this ( CH2-CH2...........so on depends on how much question demand )



Have a look at this ... hope it will help.View attachment 10358View attachment 10358View attachment 10358View attachment 10358View attachment 10358View attachment 10358View attachment 10359 View attachment 10358

heyyyyy thanks al00ot !! that reaaaly helped me, thanks soooo much =] !!!

 

[sma786]

will post more soon or give me ur email

i dun use my hotmail acc, its cl0sed =\
can u inb0x me or smthng ?

 

[kainat husain]

Question 1 (c) u have to simply find the area under the graph, that is 1/2*b*h , so 0.5*5*10.5 = 26.25
Question 8 (c) Decreases because resistance increases causing the current to decrese =)
Question 8 (d) 4 ohms, because the resistance will double ..
Alpha goes into paper because it gets absorbed , charge, alpha carries a +2 charge,
Beta goes out of paper because it can pass through paper (in tiny ammount) charge always -1 (electrons)
Gamma nothng happns, and no charge, never it carries charge,

Hope i helped =]

thank you soo much dear but still i have some doubt! in question 1 (c) the height is 12 i think :/ thn 0.5*12*5...pls make it clear ;/
and alpha can go left and righ also right or only into the paper? and which hand rule will we have to use?

 

[EpicLol]

will post more soon or give me ur email

could I have the info on polymers as well plz?

 

[AAnsarii]

In chem p6, when v draw the graph, how do v noe whether 2 draw freehand or with a scale? sby plz clarify

 

[natsume hyuga]

In chem p6, when v draw the graph, how do v noe whether 2 draw freehand or with a scale? sby plz clarify

no they tell u in the question... smooth curve is free hand but the thingis im not sure with the straight line graph thing. Gradient are almost never constant in chem.

 

[IGCSE STUDENT]

Guys please help, in Physics May June 2010 paper 31, I can't understand questions 11(b) and 5(d). Anyone please help?

 

[kainat husain]

PLEASE HELP
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w07_qp_6.pdf
q4 e-

 

[aliiiiiiiiii]

PLEASE HELP
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w07_qp_6.pdf
q4 e-

just write the marble chips will be visible after the reaction (unreacted)

 

[Mohsin41]

heyyyyy thanks al00ot !! that reaaaly helped me, thanks soooo much =] !!!

welcome

 

[shafayat]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s04_qp_3.pdf
Q7- How do we know which are compressiona and rarefactions? as the line consist same kind of '-' :/
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w04_qp_3.pdf
q-4 a (i)
q-9 a (ii)

for the first one !! u dont need to know ! just write ... compression , rerefaction,compression , rerefaction,compression , rerefaction

q 4 a (i) put the hot juction in what ever to measure n read the voltmeter reading , convert the meter reading to tempreture
q 9 a(ii) use equation v2/v1=n2/n1

 

[shafayat]

but in my book INDEX OF REFRACTION= sin i/sin r
but in marking scheme REFRACTIVE INDEX= speed in air/speed in glass

its the same !! what we learnt is
RI is refractive index
RI = sinI/sinR
RI= speed of light in air / speed of light in medium

RI= constant

 

[suhaib05]

I have two Chemistry P6 doubts and I'd really appreciate any effort to help me out:

1) http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w11_qp_62.pdf
When you use excess lumps of zinc instead of powder, does the final volume of gas produced decrease? The mark scheme says: "Sketch curve to right and below original". Even the examiner report mentions: "The sketch for the lumps curve in (ii) often went too high and joined the original graph".

2) I've noticed that in some questions, increasing the concentration of a reactant causes the final volume of gas produced to increase. In other questions, however, increasing the concentration increases the reaction rate but the final volume of gas produced remains the same. How will I know the difference?

EDIT: Never mind. I got my doubts clarified.

 

[MariamHASAN]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_62.pdf

I HAVE THE PROBLEM WITH THE LAST QUESTION OF THE CHEMISTRY 2011 PAPER 6 PLEASE HELP