Biology; Chemistry; Physics: Post your doubts here!

[ApplePie]

Does anyone know a or some youtube channel(s) which teaches igcse maths/science subjects ?

 

[asadalam]

Does anyone know a or some youtube channel(s) which teaches igcse maths/science subjects ?

Have you tried https://www.khanacademy.org/

 

[asadalam]

How is the answer B?Shouldn't it be D?
V/R=I
6/3=2
2/2(equal resistance by the resistors)=1 A in the ammeter

:/

 

[LioxMessi]

View attachment 34835

How is the answer B?Shouldn't it be D?
V/R=I
6/3=2
2/2(equal resistance by the resistors)=1 A in the ammeter

:/

PM-ed you the concept with a detailed explanation, you only had a problem with your concept.

 

[Nabeel.Ahmad]

View attachment 34835

How is the answer B?Shouldn't it be D?
V/R=I
6/3=2
2/2(equal resistance by the resistors)=1 A in the ammeter

:/

You're not looking at the placement of the Ammeter.
The question is not asking the Total current flowing through the circuit, which is definitely 1.0 Ampere.
It's asking the current flowing through the 6 Ohm resister, in Parallel, which is 0.5 Ampere, since the current will be divided into two equal parts.

 

[black widow]

View attachment 34835

How is the answer B?Shouldn't it be D?
V/R=I
6/3=2
2/2(equal resistance by the resistors)=1 A in the ammeter

:/

well like lioxmessi said ur concept is wrong
u have to find the total net resistance in the circuit
resistance across the resistors in parrallel

1/R3= 1/R1 + 1/R2

1/R3= 1/6 +1/6

1/R3=1/3

R3 = 3 ohm

total resistance in circuit= R3 + 3 ohm
= 3+3
=6

(i have used R3 to represent the total resistance of resistors connected in parrallel)

V=IR
It = 6/6
It= 1 A

since current divides when resistors are put in parrallel, the current in the ammeter will be

1/2

=0.5

 

[funky brat]

Anyone please help me with this. See question 3 (b) part 2. The statement says that the flowers belong to the same plant (monoecious plant), and the flowers no matter they are hermaphrodites or unisexual if they are pollinated from the anthers of the same plant then it's self- pollination; that is no genetic differences are involved. However the MS says that this flower is cross pollinated.
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s11_ms_62.pdf
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s11_qp_62.pdf

 

[LioxMessi]

Anyone please help me with this. See question 3 (b) part 2. The statement says that the flowers belong to the same plant (monoecious plant), and the flowers no matter they are hermaphrodites or unisexual if they are pollinated from the anthers of the same plant then it's self- pollination; that is no genetic differences are involved. However the MS says that this flower is cross pollinated.
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s11_ms_62.pdf
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Biology (5090)/5090_s11_qp_62.pdf

PM-ed you the concept with a detailed explanation.

 

[tima123]

did u check the syllabus for 2014? if it is not there, then there is no need to study it

thankx

 

[ZohaKhan]

Extraction of Aluminium: i find different things about this.. can anyonne here xplain me how is it done ? detailed!

 

[dora the explorer]

Extraction of Aluminium: i find different things about this.. can anyonne here xplain me how is it done ? detailed!

Assalm-u-alaikum. I can. I will type the entire thing and post it in around 3 hours, iA.

 

[dora the explorer]

Is it a good idea to do unsolved past papers, of Physics Chemistry and Biology?
Or should i stick to the Topical?

Now, As you have only three-ish months left till your Cies, go for the unsolved past papers. But if there is some specific topic you're not good at, then do it from the topical.

 

[asadalam]

Extraction of Aluminium: i find different things about this.. can anyonne here xplain me how is it done ? detailed!

Bauxite(al203) is purified into alumina by dissolving it in NaOH and precipitating Aluminium Hydroxide.It has a very high melting point(2800 C),and thus electrolyzing the salt would take up a lot of energy.Hence an impurity,molten cryolite Na3AlF6,is added to lower the mp to around 800 C.It is then electrolyzed in the cell and aluminium collects at the cathode and falls to the bottom of the cell,while O2 collects at anode and forms CO2 by burning the graphite(carbon) anode.Pure aluminium is siphoned off.

Thats all to it basically,any questions?

 

[ZohaKhan]

Naaaah! :') thanks alottt

 

[asadalam]

How is the answer C?Why not B?

 

[black widow]

How is the answer C?Why not B?View attachment 35469

now for such questions, u have to draw the complete ray diagram
so plot the image point point at the same distance from the mirror as the object and draw the rays

 

[funky brat]

How is the answer C?Why not B?View attachment 35469

Recall the characteristics of image formed by a plane mirror, the rays in B might meet but not as the same distance as the object is from the mirror.

 

[funky brat]

Can somebody please tell me which is the best book for Chemistry? The one which covers all the topics in detail and whole syllabus contents are there. And also which one is better, Federal Chemistry or the Chemistry Insights (the one for GCSE, I guess)?

 

[Nabeel.Ahmad]

Can somebody please tell me which is the best book for Chemistry? The one which covers all the topics in detail and whole syllabus contents are there. And also which one is better, Federal Chemistry or the Chemistry Insights (the one for GCSE, I guess)?

Federal Chemistry is better, covers most of the topics.
Many topics are missing from Chemistry Insights, like the manufacture of Sulphuric Acid by the Contact Process and the chapter about ''Water''.. and also about Natural Polymers in Organic Chemistry.

 

[funky brat]

Federal Chemistry is better, covers most of the topics.
Many topics are missing from Chemistry Insights, like the manufacture of Sulphuric Acid by the Contact Process and the chapter about ''Water''.. and also about Natural Polymers in Organic Chemistry.

Alright. But I've heard that Insights is quite detailed so would that help in anyway in getting an A*?