Physics, Chemistry and Biology: Post your doubts here!

[Ibtizam]

PHYSICS doubt - http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s11_qp_11.pdf

Question 30 and 33. Please help!!

3o is (B) B'cuz
it's open So 3+3 =6 Ohms
6v/6ohms =1 A
when it's closed 6/3 =2 A

 

[22shimmer22girly]

Asalam Mualakum Everyone,
I will be taking my IGCSE's in May/June 2013. Regarding chemistry and polymers what should i study ?? My teacher is not very helpful, I need your kind help and support. Are there and pdf notes for polymers??? I really need them.. and what else should i study for polymers ?? thank u....looking forward to your help.

 

[Ibtizam]

Asalam Mualakum Everyone,
I will be taking my IGCSE's in May/June 2013. Regarding chemistry and polymers what should i study ?? My teacher is not very helpful, I need your kind help and support. Are there and pdf notes for polymers??? I really need them.. and what else should i study for polymers ?? thank u....looking forward to your help.

https://www.xtremepapers.com/community/threads/chemistry-for-you-3.23119/

 

[therealhamzakhan]

Hello...I have a chemistry question.
It is Q5b M/J 2009
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s09_qp_3.pdf
The markscheme doesn't say much...so I'm pretty lost about this question..can you help me out?

 

[Nita Mahajan]

3o is (B) B'cuz
it's open So 3+3 =6 Ohms
6v/6ohms =1 A
when it's closed 6/3 =2 A

Hey thanks!

 

[Nita Mahajan]

nita , physics
30- A
as you have two resistors in series total resistance = u add them up
V=IR , 6=X6 X=1 and the switch wont have any affect because its placed in a wrong way
33-B
because current behaves oppositely as magnets ! because they produce magnetic fields

Sorry, but can you explain question 33... i still dont get it!

 

[Afzal1]

Question-
Explain why ethanol is not a carbohydrate but glucose is?

Can anyone help?

the three most essential elements that make up a carbohydrate are Carbon hydrogen and oxygen. which is present in glucose but not in alcohol which makes glucose an element of carbohydrate.

 

[Afzal1]

Question- Suggest an explanation why butan-1-ol cannot form long polymer molecules but ethane-1,2-diol can?

butan-1-ol does not have a double bond from between two carbon atoms but ethane-1,2-diol has a double bond between carbon atoms so it can from polymers by addition polymerisation.

 

[Afzal1]

Hello...I have a chemistry question.
It is Q5b M/J 2009
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s09_qp_3.pdf
The markscheme doesn't say much...so I'm pretty lost about this question..can you help me out?

Thats one tough question youve got there

 

[Nita Mahajan]

butan-1-ol does not have a double bond from between two carbon atoms but ethane-1,2-diol has a double bond between carbon atoms so it can from polymers by addition polymerisation.

oh.. thanks!! but can the answer also be that ethane-1,2-diol has 2 OH functional groups thats why it can form longer polymers???

 

[Nita Mahajan]

butan-1-ol does not have a double bond from between two carbon atoms but ethane-1,2-diol has a double bond between carbon atoms so it can from polymers by addition polymerisation.

Thanks!

 

[Afzal1]

oh.. thanks!! but can the answer also be that ethane-1,2-diol has 2 OH functional groups thats why it can form longer polymers???

ya ur right

 

[Afzal1]

Need help in Chemistry ????????????????

ya im ready to help

 

[Afzal1]

what is the difference in but-1-ene and but-2-ene? Can you explain what the number in between stands for?

the number denotes the place where the carbon atoms are situated (but-1-ene) means that the double bond is present between first and the second carbon atom it can be written as (butene). (but-2-ene) refers to the double bonds situated between the second and the third carbon atom. Hope u understood.

 

[MazAwesome]

Salam, can you please upload the IGCSE Bio, Chem and Phy past papers in the coming hours, I need them urgentally !!

 

[inquisitiveness]

Which device is designed to allow a small direct current (d.c.) to control a large direct current
(d.c.)?
A a generator
B a motor
C a relay
D a transformer



and how......

 

[therealhamzakhan]

A relay
Remember, a relay always controls a larger current.
A relay is a switch based on the principle of an electromagnet and when the smaller current flows through the coil the electromagnet would work and attract an iron armature on a pivot, closing contacts in a second circuit witch would have a higher current.

 

[Nita Mahajan]

Which device is designed to allow a small direct current (d.c.) to control a large direct current
(d.c.)?
A a generator
B a motor
C a relay
D a transformer
and how......

it cant be a transformer, coz it works on AC current. ITs a relay....

 

[inquisitiveness]

thanks alot guys !

 

[examkiller]

my notes in physics, i feel as they are boring, maybe someone can tell me how to grasp the topic ? as once i repeat it, i then forget about it ?? plz maybe someone can help ?thnks