Biology; Chemistry; Physics: Post your doubts here!

[asd]

but yar wouldnt particle size also effect rate of reaction???

which is why you said it would be A?

 

[ashiqbal]

which is why you said it would be A?

yes, i meant that the difference in conc. and the diff in particle size would combine to nullify each other's effect, causing the rate of reaction to be same!

the only thing i am confused is that why have they specifically mentioned "zinc pieces" and "zinc powder" if they dont intend us to use it?? or is there some other reason which doesnt depend upon "surface area affecting the speed of reaction"?

 

[asd]

yar dekho no. of moles in P are half of those in Q isi lie, hydrogen ki vol. bhi half produce hogi, to jab kam hydrogen nikalni hy to reaction jaldi proceed krega, kiyun ?
Just an inference lmao.

 

[ashiqbal]

yar dekho no. of moles in P are half of those in Q isi lie, hydrogen ki vol. bhi half produce hogi, to jab kam hydrogen nikalni hy to reaction jaldi proceed krega, kiyun ?
Just an inference lmao.

.......really, is that even possible?

 

[Spidey21]

why 20 is D? i tot muscle wont produce CO2 and only convert glucose to lactic acid with a little amount of energy? it stated 'occur first', then the answer is B? if no enough oxygen and how the concentration of CO2 in blood increase? breathing rate have to increase in order to increase oxygen intake to break down glucose to CO2 and the concentration of CO2 in blood will only increase?

wont they respire when exercise is done

 

[xcherriesx]

I think this question has been asked many times before but here goes.
should we only learn the Learning Outcomes given in syllabus ? forexaple in Physics syllabis it says students should be able to state newtons 3rd law. so no need to learn the first and second laws?
thanks

 

[scouserlfc]

.......really, is that even possible?

See i think Salman said something abt the dilute nature of solution so he may be right here but nevertheless here is my explanation for d being the answer as the solution P is very concentrated due to only 5 cm^3 having 0.20 concentration wala HCl and Q having 20cm^3 wala 0.10 concentration wala solution,so P gives u more particles per volume than Q and as a result it goes faster,the claim that particle size in Q effects the rate is correct but the thing is soltution Q is very dilute so the effect of the particle size is pretty much cancelled out here by the dilute solution so as a result D is the answer

 

[Spidey21]

See i think Salman said something abt the dilute nature of solution so he may be right here but nevertheless here is my explanation for d being the answer as the solution P is very concentrated due to only 5 cm^3 having 0.20 concentration wala HCl and Q having 20cm^3 wala 0.10 concentration wala solution,so P gives u more particles per volume than Q and as a result it goes faster,the claim that particle size in Q effects the rate is correct but the thing is soltution Q is very dilute so the effect of the particle size is pretty much cancelled out here by the dilute solution so as a result D is the answer

yeah this is exactly how its supposed to be..

 

[Fallen316]

http://www.xtremepapers.com/papers/...onal O Level/Biology (5090)/5090_s04_qp_1.pdf
please explain mcq 39

 

[ashiqbal]

http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Biology (5090)/5090_s04_qp_1.pdf
please explain mcq 39

heterozygous is (C)
this is becoz see that upon reproducing black and white, black appears only in first pair, showing black is dominant.
in second pair, we know that white is homozygous recessive, and when heterozygous reproduces with homozygous recessive, the ratio of 1:1 is observed ( in this case 2:2)
you must know these properties!

 

[ashiqbal]

and this is what you have to draw in figure of Bio ATP:
http://plantali.blogspot.com/2010/05/amyloplasts.html
http://www.els.net/WileyCDA/ElsArticle/refId-a0001294.html figure 3
http://sciweb.hfcc.net/biology/jacobs/bio131/cells/plant_cells.htm figure 3

 

[ashiqbal]

See i think Salman said something abt the dilute nature of solution so he may be right here but nevertheless here is my explanation for d being the answer as the solution P is very concentrated due to only 5 cm^3 having 0.20 concentration wala HCl and Q having 20cm^3 wala 0.10 concentration wala solution,so P gives u more particles per volume than Q and as a result it goes faster,the claim that particle size in Q effects the rate is correct but the thing is soltution Q is very dilute so the effect of the particle size is pretty much cancelled out here by the dilute solution so as a result D is the answer

yes scouser i get it but please look into my post below:

yes, i meant that the difference in conc. and the diff in particle size would combine to nullify each other's effect, causing the rate of reaction to be same!

the only thing i am confused is that why have they specifically mentioned "zinc pieces" and "zinc powder" if they dont intend us to use it?? or is there some other reason which doesnt depend upon "surface area affecting the speed of reaction"?

answer this^please, if anyone can! is this some sort of CIE trick or is this actually something included in our syllabus? please inform me

 

[asd]

heterozygous is (C)
this is becoz see that upon reproducing black and white, black appears only in first pair, showing black is dominant.
in second pair, we know that white is homozygous recessive, and when heterozygous reproduces with homozygous recessive, the ratio of 1:1 is observed ( in this case 2:2)
you must know these properties!

in simple words:
Black coat allele is dominant and it can occur in 2 genotypes, either BB or Bb. However the recessive has to be homozygous to show its characteristics.
So A and D can't be the options, since they are white which is recessive and have to be homozygous. Either it's B or C. When C is crossed with D it gives white and black both ( in a 1:1 ratio), so C must be hetrozygous.
See yourself: Bb X bb
B x b ; B x b; b x b; b x b
Bb ; Bb ; bb ; bb
2 black ; 2 white
B = dominant allele, b= recessive allele

 

[asd]

and this is what you have to draw in figure of Bio ATP:
http://plantali.blogspot.com/2010/05/amyloplasts.html
http://www.els.net/WileyCDA/ElsArticle/refId-a0001294.html figure 3
http://sciweb.hfcc.net/biology/jacobs/bio131/cells/plant_cells.htm figure 3

So you're saying the inner part was to be drawn right?

 

[fatikhalid]

i hav a few questions abt physics...
(!) is voltage directly proportional to current
(!!) is current directly proportional to resisitance??
(!!!) is temperature directly proportional to current??

me very confused abt these things anyone please help!!!..

 

[ashiqbal]

So you're saying the inner part was to be drawn right?

no! the whole part was to be drawn! the whole egg!!

 

[asd]

yes scouser i get it but please look into my post below:



answer this^please, if anyone can! is this some sort of CIE trick or is this actually something included in our syllabus? please inform me

It's like the reaction in P will be too rapid since the concentration is TOO HIGH, doesn't matter if 'pieces' are there.
While in Q, the concentration is very low yet there are more hydrogen atoms, so it will take time for all the hydrogen atoms to react. Although zinc was present in powdered form (only 1 factor to speed up the reaction), there are 2 factors to slow the rate down; low concentration and in this low concentration more hydrogen atoms. In P, only the 'pieces' (1 factor) contributed to slow the rate, while 2 factors increased the rate of reaction; High concentration, and in this high concentration less number of hydrogen atoms to react.

 

[ashiqbal]

i hav a few questions abt physics...
(!) is voltage directly proportional to current
(!!) is current directly proportional to resisitance??
(!!!) is temperature directly proportional to current??

me very confused abt these things anyone please help!!!..

(i) is correct
(ii) is inversely proportional
(iii) is correct, though i dont know about directly proportional. T increases as I increases!

 

[asd]

no! the whole part was to be drawn! the whole egg!!

I guess the egg was an INDIVIDUAL CELL. Granules are present IN the tuber cells, Y was even labelled inside the cell..

 

[ashiqbal]

It's like the reaction in P will be too rapid since the concentration is TOO HIGH, doesn't matter if 'pieces' are there.
While in Q, the concentration is very low yet there are more hydrogen atoms, so it will take time for all the hydrogen atoms to react. Although zinc was present in powdered form (only 1 factor to speed up the reaction), there are 2 factors to slow the rate down; low concentration and in this low concentration more hydrogen atoms. In P, only the 'pieces' (1 factor) contributed to slow the rate, while 2 factors increased the rate of reaction; High concentration, and in this high concentration less number of hydrogen atoms to react.

less hydrogen atoms would mean that less amount of hydrogen gas will be produced, it doesnt affect the rate of reaction!
only factors affecting rate are:
temp
concentration
surface area

the volume, mass or amount of reactants dont affect rate of reaction