Physics, Chemistry and Biology: Post your doubts here!

[ShailB]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w11_qp_32.pdfj
just 6 c
explanation
working please

Alright then
so you know the moles formula: # of moles = mass/molar mass
so you got 1.398/233 which is 0.006
now the same number of moles are used for the MgSo4 which is hydrates, as given in the equation, so 0.006 for that too
the mass of one mole is basically the molar mass. you rearrange the formula, to get 1.476/0.006 to get 246g
and then they tell you that MgS04 alone is 120. So now you subtract to leave behind the mass of water, which is 246-120 which is 126
and then you divide by the molar mass of water to get the number of moles which is basically 126/18 to get 7

 

[Taha Ahmed Baig]

Marrkscheme of Biology from year 1993-2003 paper 1,3,and6 plzz i need it

 

[Lost Pink]

8ii)... Plzzz help!

 

[Lucy Black]

condensation polymerisation removes h2o.....hence...
u can see the ans... :d
and btw...its an amide-peptide linkage(CO-NH)

 

[Lost Pink]

Can anyone help wid electrolysis in chemistry....
I mean notes or stuff...especially the equation part

 

[Nabeel Suleman]

Can some one explain addition and condensation polymers pls? thnx

 

[Hassan Zaman]

Assalam-o-Alaikum.
Post your Physics, Chemistry and Biology doubts in here and members, along with me will try their best to help you out.

i want notes for igcse cambridge \chemistry and physics

 

[Hassan Zaman]

i need the notes of igcse chemistry and physics so can anyone give me the link.

 

[Mr.Physics]

I would like to ask that What is the easiest way to learn the reactivity series and the tests for ions ???????

 

[Mr.Physics]

Can some one explain addition and condensation polymers pls? thnx

Addition polymers : Two or more than two monomers combine chemically to form an addition polymer. For ex. polyethene is formed when ethene molecules join together.
Condensation polymers: When two or more monomers combine with each other, eliminating water molecules , is called condensation polymerisation. for ex. protein is formed when amino acids combine with each other , eliminating water molecules. More examples are nylon , terylene, carbohydrates, and fats.

 

[Atharva Joshi]

Can anyone help wid electrolysis in chemistry....
I mean notes or stuff...especially the equation part

I have a presentation which my teacher gave for reference

 

[Atharva Joshi]

Stoichiometry is such a pain. Anyone have any worksheets or notes on it?
Please I require them urgently.

 

[Counter Logic Gamer]

I am having difficulties calculating the redox reactions
Ex: NO + O3=NO2 +O2
Calculating where oxidation and reduction occur......
And Simplyfying Ionic Equations:
Ex: Sn + AgNO3=......
And if possible please send notes on these sub-topics......

 

[Counter Logic Gamer]

Guys,I have a probelm in physics related to scale bearings..... can ome one help me understanding it......

 

[AliaKhan]

Thank you!! <3

 

[Phoenix Blood]

Guys,I have a probelm in physics related to scale bearings..... can ome one help me understanding it......

What don't you understand? Scale drawing?

 

[Phoenix Blood]

I am having difficulties calculating the redox reactions
Ex: NO + O3=NO2 +O2
Calculating where oxidation and reduction occur......
And Simplyfying Ionic Equations:
Ex: Sn + AgNO3=......
And if possible please send notes on these sub-topics......

Oxidation may be :
1. gain of 02
2. gain of hydrogen
3. loss of electons
Reduction is the exact opposite of it.

Redox reactions are where oxidation and reduction take place at the same time in a chemical reaction. And you don't "calculate" whether they occur or not, they just do. See in the example you gave (NO + O3 ---> NO2 +O2), nitrogen-dioxide has gained oxygen, and has thus gotten oxidized (oxidation). 03 has lost an oxygen molecule, and thus gotten reduced ( reduction). So u see? oxidation n reduction r taking place in d same chemical reaction side by side. check for the loss and gain of oxgen, hydrogen and electons in any given reaction to know whether it is redox >_>

Simplifying an equation is just how you reduce numbers in mathematics

 

[Phoenix Blood]

Stoichiometry is such a pain. Anyone have any worksheets or notes on it?
Please I require them urgently.

just 3-4 equations :

moles (for solid molecule) = mass/ar or mr
moles (for liquid) = volume*concentration
moles (for gas) = volume/24 dm3 (check if its dat only)

and some basics of balancing and stuff

 

[Phoenix Blood]

I would like to ask that What is the easiest way to learn the reactivity series and the tests for ions ???????

reactivity series (of metals n hydrogen is wat u need in d IGCSEs) :
please
stop
calling
me
a
crazy
zombie
if
that
large
hippo
can't
swim
gug glug!
plug plug!
first letter of each word denotes d first letter of each metal in order <_<

 

[Atharva Joshi]

just 3-4 equations :

moles (for solid molecule) = mass/ar or mr
moles (for liquid) = volume*concentration
moles (for gas) = volume/24 dm3 (check if its dat only)

and some basics of balancing and stuff

Ooh! I have trouble balancing