Biology; Chemistry; Physics: Post your doubts here!

[Faizan Muhammmad]

I know a water molecule is formed in condensation.
So there is no double bond broken in condensation polymerisation? Is this always true?

yep
something will get taken off (H+ or OH- ) from end of the molecules
nothing happens inside the molecule

 

[funky brat]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_w03_qp_2.pdf
Check B11. There are double bonds but the again there are two different monomers and addition polymerisation occurs.

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w03_qp_2.pdf
Check B11. There are double bonds but the again there are two different monomers and addition polymerisation occurs.

As you can see the monomers have double bonds, which are not present in the monomers of condensation polymerization. Also the monomers in condensation polymerization possess a square between the branches, which is not present here

 

[funky brat]

As you can see the monomers have double bonds, which are not present in the monomers of condensation polymerization. Also the monomers in condensation polymerization possess a square between the branches, which is not present here

Alright, thanks both of you.

 

[Faizan Muhammmad]

Alright, thanks both of you.

no problem

 

[syeda salka hashmi]

http://maxpapers.com/syllabus-materials/biology-5090/attachment/5090_s13_ms_22/

thnks

 

[exploded diper]

http://papers.xtremepapers.com/CIE/...al O Level/Chemistry (5070)/5070_s08_qp_1.pdf
question 38...answer plz.. and explain thoroughly

 

[asadalam]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf
question 38...answer plz.. and explain thoroughly

There are 2 C=C double bonds so to saturate it,we have to remove the double bonds by 2 molecules of Hydrogen.So the answer is B

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf
question 38...answer plz.. and explain thoroughly

In order to saturate it, the structure should have a structure similar to Butane
so there are 4 atoms of Hydrogen missing if we considered this to be Butane.
A molecule is a group of atoms that are covalently bonded.

The question states how many MOLECULES are needed ...
One hydrogen molecule contain 2 hydrogen atoms

So 2 molecules of Hydrogen will have 4 atoms of Hydrogen
Thus the ans. is B

 

[exploded diper]

In order to saturate it, the structure should have a structure similar to Butane
so there are 4 atoms of Hydrogen missing if we considered this to be Butane.
A molecule is a group of atoms that are covalently bonded.

The question states how many MOLECULES are needed ...
One hydrogen molecule contain 2 hydrogen atoms

So 2 molecules of Hydrogen will have 4 atoms of Hydrogen
Thus the ans. is B

ooooooohhhhhhhhhhh...........thx.......

 

[exploded diper]

There are 2 C=C double bonds so to saturate it,we have to remove the double bonds by 2 molecules of Hydrogen.So the answer is B

thx.....

 

[exploded diper]

do we have to memorize how the electro magnetic spectrum waves are genrated...

 

[Faizan Muhammmad]

do we have to memorize how the electro magnetic spectrum waves are genrated...

cant say
do them just the same

 

[Awesome12]

How exactly is the answer D. A detailed explanation would be appreciated

 

[asadalam]

How exactly is the answer D. A detailed explanation would be appreciated
View attachment 39229

As a salt of a strong acid (H2SO4) and weak base (NH3), its solution is acidic.So it will react with a base not an acid to form Ammonia.Also you can sometimes spot the 'odd one out' in MCQs to give you the answer as in this case only one option is acid while others are bases so the answer must be the one acid.

 

[Awesome12]

As a salt of a strong acid (H2SO4) and weak base (NH3), its solution is acidic.So it will react with a base not an acid to form Ammonia.Also you can sometimes spot the 'odd one out' in MCQs to give you the answer as in this case only one option is acid while others are bases so the answer must be the one acid.

Oh yeah i did read somewhere that bases react with ammonium compounds to release ammonia
Thanks for the explanation

 

[exploded diper]

Oh yeah i did read somewhere that bases react with ammonium compounds to release ammonia
Thanks for the explanation

hydrooxides react with ammonium compounds to release ammonia .......always........

 

[funky brat]

How exactly is the answer D. A detailed explanation would be appreciated
View attachment 39229

It is mentioned in the properties of Alkalis that they give off ammonia gas when warmed with ammounium salts. So all three are alkalis and would liberate ammonia gas. If ammonium sulphate reacts with H2SO4, again, ammounium sulphate and Acid forms and I don't even think this reaction would occur.

 

[Mahnoorfatima]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w10_qp_22.pdf
-Question number 1 in part bi why is the answer 47 when they've asked for a CHANGE in velocity? Plus how do you claculate ques 2 bii
-And in question number 4 the answer is that resistance INCREASES with increase in temperature but I've read it somewhere that resistance would decrease with increase in temp!
-And how to know the frequency in qs 5? Plus in a CRO while drawing the waves how will we know how much boxes do we have to draw for the xaxis as in the time base situation?
-Qs no 9 : how to draw the rays? wouldnt it get refracted ??
Please somebody explain it to me!

 

[Faizan Muhammmad]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w10_qp_22.pdf
-Question number 1 in part bi why is the answer 47 when they've asked for a CHANGE in velocity?

it was going 25 in one direction now its 22 in the opposite direction, they will be added to find change in velocity