Biology; Chemistry; Physics: Post your doubts here!

[scouserlfc]

yes man

Same here thats what made me think as well,i knew this diagram and what it is but its the weird name which just made us all curious

 

[legion]

lol i didnt name it

lol back. u explained it

 

[scouserlfc]

can anyone tell me what is the purpose of NPN transistor and potentiometer... bistable and astable circuits

I think ull be better of leaving this part its absolutely difficult to understand and most even the most renowned teachers leave this topic as it comes in optional as indicated in the syllabus so it will only be in option not in P4 or P1 either !
But if u still wanna understand then go ahead its kinda useless as u dont get it in Alevels this topic !

 

[snowbrood]

I think ull be better of leaving this part its absolutely difficult to understand and most even the most renowned teachers leave this topic as it comes in optional as indicated in the syllabus so it will only be in option not in P4 or P1 either !
But if u still wanna understand then go ahead its kinda useless as u dont get it in Alevels this topic !

yeah man its too hard i dont know why is this topic included in syllabus

 

[scouserlfc]

yeah man its too hard i dont know why is this topic included in syllabus

Just for making us go mad !

 

[awaisbuttrocksCIE]

Whats the line/curve of best fit?

 

[multixamza01]

Whats the line/curve of best fit?

the line/curve should pass through atleast 75% of the marked points. it should be a neat graph if not perfect.

 

[awaisbuttrocksCIE]

the line/curve should pass through atleast 75% of the marked points. it should be a neat graph if not perfect.

ok..thanks

 

[nightmaressana]

can someone please explain this to me? we dont have a good chemistry teacher and he doesnt explain anything, so please cooperate.
Cu does not react with H2So4 because H2 is above Cu in reactivity series.... right?
So why does CuO react with H2SO4 and in what cases will metals below Hydrogen react with acids? should they be an oxide of the metal?
please if you can, explain fully.

 

[legion]

ohh ohh. i thought copper can react with sulphuric acid. isnt this right???
http://in.answers.yahoo.com/question/index?qid=20100721014505AATIu4j

 

[multixamza01]

Your confused.

Cu cant DISPLACE H2 from any compound of H2. Condition only applies if Cu is in elematal form and H2 in Compound form. e.g if Cu is reacted with Water(H2O) nothing happens , as H2 is more reactive. Get this much. but reaction of CuO with H2SO4 is an Acid - Base Reaction. Both are in compound form. So Reactivity Series doesn't apply. Inshort. Reactivity Series displays the tendency of a metal to displace another metal from it's compund. Hope you understand.

 

[snowbrood]

ohh ohh. i thought copper can react with sulphuric acid. isnt this right???
http://in.answers.yahoo.com/question/index?qid=20100721014505AATIu4j

no as copper is not that much reactive its bellow hydrogen in reactive series

 

[nightmaressana]

thanx for helping you guys!

 

[multixamza01]

Can any one help me with D.C Motor and A.C Generator? I tried reading different books but don't seem to understand . Does any one here have any notes that could teach me this? Help will be appreciated.

 

[SalmanPakRocks]

Can any one help me with D.C Motor and A.C Generator? I tried reading different books but don't seem to understand . Does any one here have any notes that could teach me this? Help will be appreciated.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motorac.html
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdc.html#c1
check these out if u still don't understand, then i will explain it by my diagram and words.

 

[multixamza01]

thanks.

 

[SalmanPakRocks]

np

 

[hassan100]

can someone please explain this to me? we dont have a good chemistry teacher and he doesnt explain anything, so please cooperate.
Cu does not react with H2So4 because H2 is above Cu in reactivity series.... right?
So why does CuO react with H2SO4 and in what cases will metals below Hydrogen react with acids? should they be an oxide of the metal?
please if you can, explain fully.

AS fAR as i know ,I think all the metals below H in the reactivity series cannot react with dilute sulphuric acid( a point to be remembered) while there are chances that they can react with concentrated sulphuric acid!!
P.S the reaction u are talking about is a nuetralization reaction in which an acid reacts with an Alkali(CuO is a basic oxide or alkali) and as your question says "should they be an oxide of metal" this is not necessarily needed oxides act as acid or alkali in nuetralization reaction!!

 

[scouserlfc]

can someone please explain this to me? we dont have a good chemistry teacher and he doesnt explain anything, so please cooperate.
Cu does not react with H2So4 because H2 is above Cu in reactivity series.... right?
So why does CuO react with H2SO4 and in what cases will metals below Hydrogen react with acids? should they be an oxide of the metal?
please if you can, explain fully.

yup it wont react with acids but it does react with conc acids at high temperatures !
CuO reacts with sulfuric acid as multixamza said !
Dont mix it up !

 

[scouserlfc]

AS fAR as i know ,I think all the metals below H in the reactivity series cannot react with dilute sulphuric acid( a point to be remembered) while there are chances that they can react with concentrated sulphuric acid!!
P.S the reaction u are talking about is a nuetralization reaction in which an acid reacts with an Alkali(CuO is a basic oxide or alkali) and as your question says "should they be an oxide of metal" this is not necessarily needed oxides act as acid or alkali in nuetralization reaction!!

????
Well what do u mean by the bold words above !
Metal oxides act as bases while non metals act as acids and only amphoteric oxides act as both so it wud be better !