Biology; Chemistry; Physics: Post your doubts here!

[papajohn]

D is answer. image is formed where 2 rays join. as image is on the same side as object it is virtual.

I m confused..There is no ray joining??

 

[papajohn]

D is the answer..

 

[AhsanAfzal]

That is metal displacement reation..

what? displacement reaction is between more reactive element and lest reactive metal ion in compound.

 

[nidz]

http://papers.xtremepapers.com/CIE/...l O Level/Chemistry (5070)/5070_w10_qp_21.pdf

In Q.5 they are asking about the electrolysis of potassium bromide.
Why should bromine be produced, when they have not mentioned the concentration of the solution.
Shouldnt oxygen be produced? :/

 

[AhsanAfzal]

for concave lens where dotted line and the other ray join, the image is formed there. so the image is diminished

 

[starship]

Help!
View attachment 26790

which year and paper is this?

 

[starship]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w10_qp_21.pdf

In Q.5 they are asking about the electrolysis of potassium bromide.
Why should bromine be produced, when they have not mentioned the concentration of the solution.
Shouldnt oxygen be produced? :/

Bromine moves towards the anode thats why the colour goes brown.

 

[AhsanAfzal]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w10_qp_21.pdf

In Q.5 they are asking about the electrolysis of potassium bromide.
Why should bromine be produced, when they have not mentioned the concentration of the solution.
Shouldnt oxygen be produced? :/

take aqueous as concentrated if it is not mentioned whether it is dilute or concentrated.

 

[starship]

for concave lens where dotted line and the other ray join, the image is formed there. so the image is diminished

so this the image?

 

[Mohammad Mishal]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w10_qp_21.pdf

In Q.5 they are asking about the electrolysis of potassium bromide.
Why should bromine be produced, when they have not mentioned the concentration of the solution.
Shouldnt oxygen be produced? :/

sorry! but where does it says bromine is produced?

 

[starship]

take aqueous as concentrated if it is not mentioned whether it is dilute or concentrated.

Umm why?

 

[starship]

sorry! but where does it says bromine is produced?

exactly my point. it moves towards the anode but isnt produced!

 

[papajohn]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_w10_qp_21.pdf

In Q.5 they are asking about the electrolysis of potassium bromide.
Why should bromine be produced, when they have not mentioned the concentration of the solution.
Shouldnt oxygen be produced? :/

First of all, aqeuous means it contain OH- and H+ ions nothing to do with concentration. Oxygen will produce only if they mention that it is dilluted.

 

[AhsanAfzal]

so this the image? View attachment 26793

yes

 

[Saad Mughal]

Help!
View attachment 26790

The answer is D. Remember, for diverging lens, the image is ALWAYS virtual and smaller.

 

[AhsanAfzal]

Umm why?

i asked this question yesterday and got this answer

 

[AhsanAfzal]

can salt react with alkali in D to produce salt???

 

[starship]

i asked this question yesterday and got this answer

It doesnt make any sense :/ Besides I haven't come across any question that asks for the products and doesnt tell if the sol is concentrated or dilute

 

[Saad Mughal]

View attachment 26791
how will D produce a salt? how is salt formed from salt+alkali? pls explain @suchal saad muhghal

We've gone through this a couple of times now. The sulphate ion SO2 (2-) is the more stable ion than hydroxide so the sodium displaces the copper to form a bond with the preferred stable sulphate ion.

 

[starship]

View attachment 26795
can salt react with alkali???

If you're not sure about that leave it
look at the other options
Its confirmed that Cu would be produced along with water In b-no salt is produced...