Physics, Chemistry and Biology: Post your doubts here!

[Reddah Nadeem]

8th of may

oh mines on 8th may

 

[Reddah Nadeem]

How to remember if a substance is soluble or not ????

If it dissolves in a solvent (like water) then it is soluble.

 

[Reddah Nadeem]

jacepang when is ur chemistry ppr??

 

[Princess Raven]

m

How to remember if a substance is soluble or not ????

memorize the solubility rules

 

[Princess Raven]

theres is no topic on Ray Tracing in my book, can some one plz give me its notes or ...?

its really common sense.. ur talking about physics p6 right?

 

[Princess Raven]

jacepang when is ur chemistry ppr??

everyones paper is on the 8th.. worldwide

 

[Princess Raven]

yes ok look its a reversible rxn so by adding water the colour will change to pink.. and in the first reaction temp decreases as heat is given off the reverse is temp increases thus its b

assalamo3alaykum, In chemistry paper 1 does anyone now how to get the answer in question 16 here is the exam http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_12.pdf

 

[zain1245780]

its really common sense.. ur talking about physics p6 right?

yes. atp. can you plz answer my other questions too?

can someone plz tell me the correct position for a voltmeter in Q3.a and the position of rheostat in Q3.d? below is the link. and one more question, all the readings i take from my scale (meter rule) are lesser than the ones in mark scheme, there is a big difference, i have also changed my scale but the result is same, why is it so? thanks in advance. http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w12_ms_62.pdf

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s08_qp_1.pdf
question no 26 Plz explain y is the answer D??

Have a look at the Periodic table Metals form Positive ions! and all the others are non metals
I hope you got it

 

[IGCESs monster]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Mathematics (0580)/0580_s08_qp_2.pdf
Question 11
Please answer!

 

[Ahmed Shazly]

yes ok look its a reversible rxn so by adding water the colour will change to pink.. and in the first reaction temp decreases as heat is given off the reverse is temp increases thus its b

Thanks alot for your help

 

[ZaqZainab]

hey guys, im going to sit my IG's this week ! i need help with bio paper 6, what topics should i revise for this paper?

The tests for start,fats, Protein.....
How to destarch a leaf
What a control is
How to improve investigation!
Safety in a investigation
What should be constant during an Investigation
Thats all i have done

 

[amxrox1]

The tests for start,fats, Protein.....
How to destarch a leaf
What a control is
How to improve investigation!
Safety in a investigation
What should be constant during an Investigation
Thats all i have done

thnku sooo much !! whats a control btw?

 

[ZaqZainab]

thnku sooo much !! whats a control btw?

Don't tell me you are giving your exam and you don't know what a control is!
Well i suck at explaining but do try to google it
its like you keep it with actual conditions
lets take an example a person is try to figure out if placing a plant side ways makes a difference he does 3 experiments
in 1 he rotates the plant side ways
in 2 he keeps it still side way
in 3 he keeps it upright
here the control is 3 like it is not applied to the conditions(here is is keeping the plant side ways)
in short a control is an experiment you do where you don't change the variables

 

[amxrox1]

ohhh i get it !! thnx !

 

[ZaqZainab]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s12_qp_33.pdf

Question 11 b
how is the answer 1.2-1.8 day?
how to deduct the background reading?

please help.

Now this is kinda Mind wrecking but logical
SO here we go now you know after 6 days it is the background radiations
and if you go to the y axis for 6 days it is 16 counts per min
now 52-16=36
the full life is 36
36/2 gives the half life of the sample
18 now 18+16=34
34 of y axis is 1.6 on the x axis
Yay we got it in the middle of 1.2 and 1.8

 

[Ahmed Alaa El-shamy]

BIOLOGY Can someone help me please
There is a question in OCT/NOV 2005 Paper 6
Suggest how you would observe the yeast cells and how you would estimate their total population in the flask?
i looked it up in the marking scheme but still i don't understand the answer :'(
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Biology (0610)/0610_w05_qp_6.pdf

Q3 a)

 

[ZaqZainab]

yes. atp. can you plz answer my other questions too?

can someone plz tell me the correct position for a voltmeter in Q3.a and the position of rheostat in Q3.d? below is the link. and one more question, all the readings i take from my scale (meter rule) are lesser than the ones in mark scheme, there is a big difference, i have also changed my scale but the result is same, why is it so? thanks in advance. http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w12_ms_62.pdf

You're Questions are really easy
3a is parallel to the lamps
3d- is i unit is 0.02 amps so postion one is 2 units ahead of 0.8
0.8+0.02+0.02=0.04 And so on with the other

 

[ZaqZainab]

BIOLOGY Can someone help me please
There is a question in OCT/NOV 2005 Paper 6
Suggest how you would observe the yeast cells and how you would estimate their total population in the flask?
i looked it up in the marking scheme but still i don't understand the answer :'(
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Biology (0610)/0610_w05_qp_6.pdf

Q3 a)

Nice doubt i have the same doubt!
But lemme tell you what i got using a microscope because yeast cells are really tiny its like you at least need a microscope with 400x power To count cells, you use a slide with tiny etched squares,know as the cell counter. the etched squares are made precise ,so the contained volume is know. Now to make them visible we stain the cells thats what i only get

 

[Ahmed Alaa El-shamy]

Nice doubt i have the same doubt!
But lemme tell you what i got using a microscope because yeast cells are really tiny its like you at least need a microscope with 400x power To count cells, you use a slide with tiny etched squares,know as the cell counter. the etched squares are made precise ,so the contained volume is know. Now to make them visible we stain the cells thats what i only get

so i should Answer like that: Use a microscope to observe the Yest cells using a high magnification, place yeast cells on a cell counter and stain them to make them visible. ( well i guess that answers almost more than half of the question THANK YOU ) i guess what is missing now is to know how to estimate their total population ?