Biology; Chemistry; Physics: Post your doubts here!

[darkvoid]

Post the link of the other video
it wont playy

For moles practice as much as you can , I know there is less time but still. Once you get the hang of it , its damn easy

 

[bogus]

The answer is actually C even i thought it was C at first

Can you tell me which paper is this? as in the year and the session.

 

[darkvoid]

Can you tell me which paper is this? as in the year and the session.

May/June 2014 p11

 

[Parhaakoo]

Can anyone tell me what will be produced at anode in electrolysis of aqueous solution of KBr? (it isn't specified if it is dilute or concentrated)

 

[Error Syntax]

Can anyone tell me what will be produced at anode in electrolysis of aqueous solution of KBr? (it isn't specified if it is dilute or concentrated)

It is Bromine that will be released into the anode. it is because bromine is lesser in the displacement series, lower than OH- .

 

[Parhaakoo]

It is Bromine that will be released into the anode. it is because bromine is lesser in the displacement series, lower than OH- .

Isn't OH at the end?

 

[darkvoid]

It is Bromine that will be released into the anode. it is because bromine is lesser in the displacement series, lower than OH- .

I believe hydrogen will be produced. Since the solution is aqueous OH- will be selectively discharged. Generally in past paper questions unless the solution is stated to be concentrated it always means it is dilute. Also the displacement series is only taken into regard when deciding on displacement of cations.

 

[smiling star]

Can anyone tell me why A is the correct answer?

 

[smiling star]

And why B is the correct answer in this one?

 

[darkvoid]

And why B is the correct answer in this one?View attachment 60447

A, because plants make oxygen using photosynthesis which takes place when there is sunlight. During midnight (12 a.m) there would be no sunlight and no photosynthesis so no oxygen.

B, because in the structure of a plant stem or tree bark, phloem is located on the outer region and xylem in the inner region. When the ring of bark is removed , phloem is removed and since it is responsible for translocation of nutrients (amino acids , sucrose) from leaves to roots (and other storage organs) , the plant will die due to lack of nutrition.

Hope this helped, good luck for exams!

 

[Parhaakoo]

I believe hydrogen will be produced. Since the solution is aqueous OH- will be selectively discharged. Generally in past paper questions unless the solution is stated to be concentrated it always means it is dilute. Also the displacement series is only taken into regard when deciding on displacement of cations.

Yeah I thought so too, but the marking scheme states bromine is discharged. So confusing

 

[darkvoid]

Yeah I thought so too, but the marking scheme states bromine is discharged. So confusing

The mark scheme must be wrong then

 

[bogus]

The mark scheme must be wrong then

No its Bromine. This question is about a concentrated solution as it only says aqueous' so we assume in this case that it is concentrated unless they themselves have said that it is dilute. For concentrated solutions the rule is slightly different. The solute ie any compound you add (other than water) will always discharge provided that it is not TOO reactive like SO4. Bromine is not , there fore it will be discharged at the anode

 

[darkvoid]

No its Bromine. This question is about a concentrated solution as it only says aqueous' so we assume in this case that it is concentrated unless they themselves have said that it is dilute. For concentrated solutions the rule is slightly different. The solute ie any compound you add (other than water) will always discharge provided that it is not TOO reactive like SO4. Bromine is not , there fore it will be discharged at the anode

Do you have a link to the question by any chance? I want to see it for myself. Is it p1 or p2?
If it is concentrated then obviously bromine will be discharged

 

[smiling star]

A, because plants make oxygen using photosynthesis which takes place when there is sunlight. During midnight (12 a.m) there would be no sunlight and no photosynthesis so no oxygen.

B, because in the structure of a plant stem or tree bark, phloem is located on the outer region and xylem in the inner region. When the ring of bark is removed , phloem is removed and since it is responsible for translocation of nutrients (amino acids , sucrose) from leaves to roots (and other storage organs) , the plant will die due to lack of nutrition.

Hope this helped, good luck for exams!

Thanks a lot and good luck to you too:')
Only a few days remaining and the stress just adds up..

 

[Error Syntax]

Thanks a lot and good luck to you too:')
Only a few days remaining and the stress just adds up..

How much have you done bro?

 

[bogus]

Do you have a link to the question by any chance? I want to see it for myself. Is it p1 or p2?
If it is concentrated then obviously bromine will be discharged

I don't but if it isn't mentioned that something is dilute, we automatically assume that it is aqueous.

 

[bogus]

I know this is a bit off-topic, but does anyone know how to write an article?

 

[Khawaja Shoaib]

what about physics atp.. it seemed to be very strange this time.. no question was from electronics.. wasnt the paper a bit difficult.. how did u use the set squares to find the rod was horizontal (i knew how to do it with a ruler).. and what about the very last experiment?? what did u do in that?
what do you think about the threshold this time, will it be higher or will it go down??

 

[Parhaakoo]

what about physics atp.. it seemed to be very strange this time.. no question was from electronics.. wasnt the paper a bit difficult.. how did u use the set squares to find the rod was horizontal (i knew how to do it with a ruler).. and what about the very last experiment?? what did u do in that?
what do you think about the threshold this time, will it be higher or will it go down??

Yeah set square one was confusing. As for last question, one way to do it was to find the circumference and then use the formula for circumference to find the diameter.