POST YOUR BIO AND CHEM PAPER 1 DOUBT HERE !!!!

[Besterlinks]

I think the anser should be D.. this is because the mixture of ammonia and nitrogen will not react or dissolve in water and hence, the gas will remain intact. In other answers, eg. A, sodium hydroxide will react with carbon dioxide to form sodium carbonate! Hope I helped..

Why can't it be C?

 

[Alool]

Some barium iodide is dissolved in water.
Aqueous lead(II) nitrate is added to the solution until no more precipitate forms.
This precipitate, X, is filtered off.
Dilute sulfuric acid is added to the filtrate and another precipitate, Y, forms.
What are the colours of precipitates X and Y?
___X_____Y___
A white__white
B white__yellow
C yellow__white
D yellow__yellow

 

[saroooor]

Some barium iodide is dissolved in water.
Aqueous lead(II) nitrate is added to the solution until no more precipitate forms.
This precipitate, X, is filtered off.
Dilute sulfuric acid is added to the filtrate and another precipitate, Y, forms.
What are the colours of precipitates X and Y?
___X_____Y___
A white__white
B white__yellow
C yellow__white
D yellow__yellow

C . Yellow precipitate for lead iodide . White precipitate for barium sulphate ( sulphuric acid reacting with barium nitrate . )

 

[Besterlinks]

Some barium iodide is dissolved in water.
Aqueous lead(II) nitrate is added to the solution until no more precipitate forms.
This precipitate, X, is filtered off.
Dilute sulfuric acid is added to the filtrate and another precipitate, Y, forms.
What are the colours of precipitates X and Y?
___X_____Y___
A white__white
B white__yellow
C yellow__white
D yellow__yellow

It is C.

First, you get lead (II) iodide, which is yellow owing to the iodide cations (you need to look up ion tests if you don't know this...)

The solution (the solution) consists of barium and nitrate ions. When you add sulfuric acid, barium ions react with sulfate ions to form barium sulfate, which is white in colour (again, refer to ion tests).

Hope this helps

 

[Jspake]

Why can't it be C?

Ammonia is soluble in water!

 

[saroooor]

C . Yellow precipitate for lead iodide . White precipitate for barium sulphate ( sulphuric acid reacting with barium nitrate . )

I believe so .. make sense ?

 

[Besterlinks]

Ammonia is soluble in water!

Crap

 

[Rania MD]

can anyone please pretty please give me the biology and chemistry papers of 2000 and 2001 summer and winter ?

 

[Jspake]

Please help me solve this question.. it got me thinking really hard!

 

[сᴏᴏʟ сяуѕтᴀʟѕ]

Assalam-o-alaikum wr wb...

Please help me solve this question.. it got me thinking really hard!

well what you have to do is write a combustion equation for the reaction (in order to find the answer you need to write for all...) if you want me to write for all...you surely can ask

balance this equation...

C6H9OH + 8O2 --------> 6CO2 + 5H2O

for one molecule of C6H9OH you need 8 molecules of Oxygen...so the answer is B

any doubt?

 

[saroooor]

Please help me solve this question.. it got me thinking really hard!

Assailam alaikum wr wb
I can help . You write a regular reaction with oxygen with all the organics available with oxygen were the ratio has to be 1 to 8 for the organic compound . For example X(organic compound ) + 802 - co2 + h20 ( balanced correctly ). You do this with all the organic compounds available . in B it will be the most suitable since C6H9OH + 802 -> 6co2 + 5H2o You just balance the products since the reactants are already balanced a 1:8 ratio (reactants ) , so B is the most suitable . That's what I believe . Make sense .....?

 

[Besterlinks]

Please help me here with QUESTION 21 in the attached PDF.

 

[Jspake]

Assalam-o-alaikum wr wb...

Assailam alaikum wr wb
I can help . You write a regular reaction with oxygen with all the organics available with oxygen were the ratio has to be 1 to 8 for the organic compound . For example X(organic compound ) + 802 - co2 + h20 ( balanced correctly ). You do this with all the organic compounds available . in B it will be the most suitable since C6H9OH + 802 -> 6co2 + 5H2o You just balance the products since the reactants are already balanced a 1:8 ratio (reactants ) , so B is the most suitable . That's what I believe . Make sense .....?

Yeah.. i did that.. but I was expecting an easier way of solving it. So u actually hv to balance all the equations given?? That's so time consuming! Thanks anyways..

 

[saroooor]

Please help me here with QUESTION 21 in the attached PDF.

Is it B ?

 

[Alool]

It is C.

First, you get lead (II) iodide, which is yellow owing to the iodide cations (you need to look up ion tests if you don't know this...)

The solution (the solution) consists of barium and nitrate ions. When you add sulfuric acid, barium ions react with sulfate ions to form barium sulfate, which is white in colour (again, refer to ion tests).

Hope this helps

thankew! yeah actually i thought of that but was not sure.. thanks again

 

[Rahma Abdelrahman]

Please help me here with QUESTION 21 in the attached PDF.

I believe it's C as potassium is so reactive that you can't use the metal itself.
I am not sure of this ans. btw!

 

[salvatore]

Please help me here with QUESTION 21 in the attached PDF.

The answer should be B.. potassium will replace hydrogen from HCL when a metal alone, potassium hydroxide or potassium carbonate.. forming potassium chloride!

 

[Rahma Abdelrahman]

thankew! yeah actually i thought of that but was not sure.. thanks again

Besterlinks , iodide ions are anions not cations !

 

[Tekno-M]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Biology (0610)/0610_w09_qp_11.pdf
Can someone explain why number 19 is B?

 

[salvatore]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Biology (0610)/0610_w09_qp_11.pdf
Can someone explain why number 19 is B?

It's D! Check the marking scheme again..