Biology; Chemistry; Physics: Post your doubts here!

[Mayedah]

Your late Haha

Better late than never

 

[SalmanPakRocks]

Better late than never

I was kidding

 

[asd]

And then i think the pictures were misleading because both do come from the same point and if u have done MCQs and Theory papers u will know for urself that it comes from the same place

If u want a proof ill tell u the papers year !

Maybe they come out from the same point in epigeal germination, and not in hypogeal germination ..

 

[selgomez]

(i) 2HCl (aq) + CaCO3 (s) → CaCl2(aq) + H2O (l) + CO2 (g)

(ii) no. of moles of HCL = 1.5 * 25/1000 = 0.0375 mol
2 : 1
0.0375: x
2x = 0.0375
x = 0.01875 * 24 = 0.45 dm^3

the answer in the marking scheme is 0.9dm3. That's what's confusing me!!
Its question 5 from Nov05: http://www.xtremepapers.com/papers/...al O Level/Chemistry (5070)/5070_w05_qp_2.pdf

 

[SalmanPakRocks]

the answer in the marking scheme is 0.9dm3. That's what's confusing me!!
Its question 5 from Nov05: http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_w05_qp_2.pdf

0.9? Let me see.

 

[selgomez]

0.9? Let me see.

I've tried to make sense out of it but the answer should be 0.45dm3 ..

 

[SalmanPakRocks]

I've tried to make sense out of it but the answer should be 0.45dm3 ..

Did you check the answer in examiner report?

 

[selgomez]

Did you check the answer in examiner report?

This is all it says: "(a) State symbols posed no problems for most, although there was some confusion between the use
of (aq) and (l). Some thought that calcium carbonate was an aqueous solution. The calculation
proved difficult for many candidates. This is a standard type of calculation and many Examiners
commented that fewer candidates than expected were able to work to give the correct answer. "
Not helpful in answering the question ..

 

[SalmanPakRocks]

This is all it says: "(a) State symbols posed no problems for most, although there was some confusion between the use
of (aq) and (l). Some thought that calcium carbonate was an aqueous solution. The calculation
proved difficult for many candidates. This is a standard type of calculation and many Examiners
commented that fewer candidates than expected were able to work to give the correct answer. "
Not helpful in answering the question ..

Isn't answer present at the end?

 

[selgomez]

Isn't answer present at the end?

Nope. I've posted the entire paragraph related to that question.
The answer in the marking scheme is: "ii. 25/1000 x 1.5 x 24 = 0.9 dm3 / 900 cm3"

 

[SalmanPakRocks]

Nope. I've posted the entire paragraph related to that question.
The answer in the marking scheme is: "ii. 25/1000 x 1.5 x 24 = 0.9 dm3 / 900 cm3"

What? That can't be possible! This is an error

 

[selgomez]

What? That can't be possible! This is an error

Do they usually make errors at this level??

 

[SalmanPakRocks]

Do they usually make errors at this level??

Well some times there are errors in marking scheme

 

[Spidey21]

This is totally shit, I've seen pictures-some show they come out from the same point on the testa, while others show that plumule grow out from the top, and radicle from the bottom/middle of the testa.

thats not the testa...they come out from the middle and then EXTEND towards the following
Radicle extends towards the lower side while plumule goes up...hope you understand...

http://www.google.com.pk/imgres?q=s...7&start=10&ndsp=27&ved=1t:429,r:14,s:10,i:189

i hope this will help you...

 

[Spidey21]

Multiply 25 with 1.5 =37.5
Now divide the answer by 1000
It will be 0.0375
Now from the equation u can see tht 2 moles of hcl react with one mole of carbondioxide so divide answer by 2
0.0375/2=0.01875
Now mltiply this answer with 24 to find volume
0.01875x24= 0.45

well...if they asked the mass then that would 0.9g but however as they are asking for volume that should be 0.45 dm3..:|

 

[Mayedah]

well...if they asked the mass then that would 0.9g but however as they are asking for volume that should be 0.45 dm3..:|

Nope. I've posted the entire paragraph related to that question.
The answer in the marking scheme is: "ii. 25/1000 x 1.5 x 24 = 0.9 dm3 / 900 cm3"

Yes the answer will be 0.45 not 0.9 !

 

[Spidey21]

Yes the answer will be 0.45 not 0.9 !

it would be 0.9 only in the case they want the mass..

cuz mass=mole x Mr

 

[Mayedah]

it would be 0.9 only in the case they want the mass..

cuz mass=mole x Mr

Yup

 

[Spidey21]

Yup

so we hit this on the face of the examiner??

 

[SalmanPakRocks]

so we hit this on the face of the examiner??

CIE would not enter into discussion over the answers from Marking Scheme or Examiner report! It's written on the first page.