Physics, Chemistry and Biology: Post your doubts here!

[Wasif`]

yeah best of luck
pray for me

thanx & ya sure

 

[sma786]

Can anybody gimme an example of an acidic oxide?

 

[Moi]

how did the paper go??

all i can say.. worst paer ever !!
coudn't complete it in time Left un answered question

 

[sma786]

any help need in chemistry????? i will help but just remmember me in prayers!!!!!

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_31.pdf
Question 3 (b) please explain this ..
Question 4 (b) , how do we know it will turn brown ??
Question 4 (c) can you draw the figure for me.. ?

 

[thats_me]

Can anybody gimme an example of an acidic oxide?

oxides of non-metals usually eg: Carbon dioxide , Sulphur dioxide ,Nitrogen dioxide...

 

[thats_me]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_31.pdf
Question 3 (b) please explain this ..
Question 4 (b) , how do we know it will turn brown ??
Question 4 (c) can you draw the figure for me.. ?

3b: One of the uses of zinc is galvanising ,In this method the metal (zinc) protects steel objects from rusting to do this the zinc coating rusts instead of steel... Here Zinc( being more reactive )is oxidised in preference to iron by loosing its electrons and forming ions ...
4b: you need to learn this Oxidising agent + potassium iodide : colour changes from colourless to brown

 

[kboss]

how should we draw the alkanes, alkenes, isomers in form A or form B?

Form A)

Form B)

 

[Yousif Mukkhtar]

how should we draw the alkanes, alkenes, isomers in form A or form B?

Form A)

Form B)

Both are accepted.

 

[kboss]

Both are accepted.

thanks
thats a relief cuz my teacher wasn't sure if Form B was accepted and i find it much easier...

 

[kboss]

for temp. and pressure of contact process do we have to give a range or a specific value???
e.g for contact process can we write 450 or do we have to write 400-450??
and for pressure can we just write 2 or do we have to write 1-10 atm?

 

[NIM]

Guys need help!!!
1) How is zinc oxide obtained from zinc sulfide???
2) During electrolysis, it is necessary to add more chromium(III) sulfate but during
copper-plating using a copper anode, it is not necessary to add more copper(II)
sulfate. Explain???
3) What is meant by the term carbohydrate?

 

[kainat husain]

HOW TO DRAW THERE :/
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_w05_qp_6.pdf
Q-1 C
q-2 a
i am really confused please some one help

 

[thats_me]

Guys need help!!!
1) How is zinc oxide obtained from zinc sulfide???
2) During electrolysis, it is necessary to add more chromium(III) sulfate but during
copper-plating using a copper anode, it is not necessary to add more copper(II)
sulfate. Explain???
3) What is meant by the term carbohydrate?

1: By heating ZInc Sulfide in air which forms Zinc Oxide and Sulfur dioxide
2ZnS + 3O2 -->2ZnO +2SO2
2:As In copper plating the electrolyte is not used up, it doesnot take part in the reaction But with chromium Sulphate it is used up to replace chromium ions ...
3:It is a compound which consists of carbon, hydrogen and oxygen present in the same ratio as water.

 

[thats_me]

for temp. and pressure of contact process do we have to give a range or a specific value???
e.g for contact process can we write 450 or do we have to write 400-450??
and for pressure can we just write 2 or do we have to write 1-10 atm?

I think both can be given... But the specifc value should be with in the range..

 

[Solostar]

My maths doubt

1) A group of friends share a bill of $13.69 equally between them. How many were there in the group?

2) Put four different numbers in the circles so that when you add the numbers at the end of each line you always get a square number.

 

[balloonsandhighlighters]

Hi everyone

Please can you guys explain structural isomerism? First off, how do we draw an isomer as apparently there are different ways to do so (i think 2?) and also, how do we name them, because the steps for naming the isomer is different for each homologous series. For instance, methylpropane is the isomer for butANE, whereas but-1-ene is an isomer for butENE.


Thank you so much in advance!! I tried looking it up on the internet, but nothing of use came up! And also I looked at the A-level notes on here, but they're not helpful Thanks again - truly appreciate it!


Balloons. And highlighters. Yar.

 

[NIM]

1: By heating ZInc Sulfide in air which forms Zinc Oxide and Sulfur dioxide
2ZnS + 3O2 -->2ZnO +2SO2
2:As In copper plating the electrolyte is not used up, it doesnot take part in the reaction But with chromium Sulphate it is used up to replace chromium ions ...
3:It is a compound which consists of carbon, hydrogen and oxygen present in the same ratio as water.

ok thnx...
i got it!!!

 

[thats_me]

ok thnx...
i got it!!!

np

 

[NIM]

i don't know i feel headache while doing chemical calculations (stoichiometry).... and still i didnt get stoichiometry chap!!!

 

[Manobilly]

Try solving them try ,the book is a great help,than ask for any doubts.