Bio p33 dicussion..

[ahmedrik1501]

Okay guys i guess 24 hours of waiting are on verge of waiting.. So lets now discuss the Bio practical 33.

Okay what was the actual length i got 254Um
and do we need to label something else in hight power drawing of trichomes and epidermis other then trichomes and epidermis themselves.

 

[filza94]

FOR Chemistry PAPER 33!!!!!!!!!!

hydrated ammonim salt titrated with KMnO4
usual salt analysis
one thermal question

We have to titrate ammonium nitrate with KMn04 or would we need to oxidize potassium iodide in the presence of ammonium nitrate and then titrate the resulting solution with sodium thiosulphate? :|

see question no.1 in june2008-31
a similar question is expected!


FOR PHYSICS ASLEVEL PAPER 33

what we hav been practicing is the electricity one with beads in place of resistors.its very simple..and ya in the oscillation one we will be having a cylinder instead of a pendulam bob..

i doubt anything concerning magnets or diodes on A2 level will come for As practicals, hmm, they might just be giving diode as just another component of the circuit system, in past years there were things like that, but the procedure is still the same, you will just have to either measure current, volt etc. and draw the graph, and by the way it will be helpful to review the graphs for diodes. before going for exam.

YOU WILL NEED
1.retort stand.
2.bob/cylinder
3.stopwatch.
4.thread
5.multimeters
6.batteries
7.clamps.
8.resistors.
9.contacts

 

[ahmedrik1501]

yeah i have read your poxt many times thanks

 

[mrpaudel]

yea for biop33..i too got 254 micro metre..!!

 

[BILALrox01]

254 for me ..... anyways what i wanted to know is did u people get enough enzyme because we weren't able to complete the experiment with our quota.. I had to just random guess the answer to time and they aren't anywhere near all of the others. who too guessed but were closer to each other. Will I b penalized.. and if so how much. And in the trichome.. what did u draw in the drawing.. did u guys draw any nucleus etc??

 

[Amberkgkl]

Does anybody have guesses for p 34 ?

 

[FreePalestine93]

Ystrday i had BIO-33 and ...Mann....this was probably the worst practical EVERR !!!.. especially Q1 serial dilutions one...i didnt get it until the end wen it waz over.. i made the dilutions in the test tubes n'd kept dumping bak and forth in petri dishes.. ahhh.. it Was a KILLER !!! nd' i was trying 2 figure out how the syringe wud fit into dee test tube at dee beginning... I think most other ppl felt the same way !!..
I messed up BIG TIMe in the first Question...i had to do it(dilutions) over again...nd i cudnt take readings so i just made the table wid headings..bcz that also has a few marks doesn't it ?
nd Plus the light kept going out in Q2 (microscope).. that wasted allota time...n' the head invigilator only gav 5 mins extra compensation at d end.. and that too only aftr i argued wid him soo much...i told him "LOOK, IT'S 2 HRS WIDOUT LOADSHEDDING" n' it was a scene :lol: lolzz..he felt offended cuz i talked BAKK Straight up...Ahhh he was a Douche-Bag !! u know how British Council invigilators are (Rude n' Arrogant !) .. Them nd' their EGO..buh i surely embarrassed him lolzz,....that was probably the best part :Bravo: of d xam lozlzz :lol: !!!

btw I've noticed from many ppl in the forums who gave other variants of Bio pract like 31... they had the same Q2 wid the trichomes buh Q1 was slightly different. although concept(Serial Dilution) nd' apparatus was same !

 

[filza94]

ur welcum ahmed.....

http://www.scribd.com/doc/6468212/Teach ... cal-Skills take dix for praticals

 

[filza94]

Anyone please explain it in a simple, understandable way. Thanks.

 

[Anonymousx3]

What about the percentage decrease question?
I got 12.2 but some people got 13.8 or something. :x

 

[ahmedrik1501]

12.2% yippieee...

 

[filza94]

hey guyz recent info i got for u ppl for chemistry ppr 33

my class fellow get information that FA1 is ammonium iron salt for heating, Q2 is reaction KMnO4 with KI in the presence of H2SO4, then titration with Na2S2O3...and Q3 contain Ammonium Bromide and zincsulfate salts.....

 

[ahmedrik1501]

Anyone please explain it in a simple, understandable way. Thanks.

Ah Filza is it As level question.... Well even if it is not what you have to do in this question is simple and sweet....
See every salt in the world has certain level of solubility in water. Like wise this salt has following solubility in water (thanks to wikipedia):
133 g/L (0 °C)
360 g/L (25 °C)
2470 g/L (100 °C)

u can see that at different temperature the solubility is different. Here the temperature is kept at 60 °C constantly that is it is not changing and it will stay the same using some computerized heater or something (thermostatically controlled means to control via a thermostat). Moving forward now to calculate the solubility.

measure a measuring cylinder.
Decant the saturated solution in order to make sure that no extra salt is there.
note down the volume of water
as density of water is 1g/cm3 hence mass of water is also same as its volume (in cm3)
after that remeasure the cylinder and note the new mass
from the new mass measure subtract the mass of cylinder and water
what ever left is the mass of salt in soultion.

then use unitary method to find the solubility i.e.
if x mass of solvent is dissolved completely in y volume of water at 60 °C then
how much mass is soluble in 1l i.e. 1 dm3 or 1000cm3.

 

[filza94]

okay i got it by how wil we rite da steps is da question.....

 

[ahmedrik1501]

okay i got it by how wil we rite da steps is da question.....

I dnt got u

 

[filza94]

i mean watz da answer for that question????

 

[zahraahmed]

this is what the examiners say abt titrations:
Titrations were generally performed well. Burette readings for “accurate” titrations were recorded
to 2 decimal places (nearest 0.05 cm as required by the syllabus). The Examiners were pleased
to see that few candidates recorded “impossible” burette readings such as 27.43 cm
The majority of candidates produced consistent titres as described in the syllabus (2 titres within 0.10 cm3
. Many candidates, having obtained two titres within 0.10 cm wasted time by performing
further titrations: 3, or even 4, identical titres or titres within 0.10 cm3 was not unusual
The selection of titres for calculation of the “average” was less successfully performed. Many
candidates ticked only one titre. In this case Examiners accepted the candidate’s chosen value
when assessing accuracy. The difference between the chosen value and the next nearest was
used to calculate spread, and a penalty applied if necessary.

 

[zahraahmed]

this is what the examiners say abt titrations:
Titrations were generally performed well. Burette readings for “accurate” titrations were recorded
to 2 decimal places (nearest 0.05 cm as required by the syllabus). The Examiners were pleased
to see that few candidates recorded “impossible” burette readings such as 27.43 cm
The majority of candidates produced consistent titres as described in the syllabus (2 titres within 0.10 cm3
. Many candidates, having obtained two titres within 0.10 cm wasted time by performing
further titrations: 3, or even 4, identical titres or titres within 0.10 cm3 was not unusual
The selection of titres for calculation of the “average” was less successfully performed. Many
candidates ticked only one titre. In this case Examiners accepted the candidate’s chosen value
when assessing accuracy. The difference between the chosen value and the next nearest was
used to calculate spread, and a penalty applied if necessary.

 

[ahmedrik1501]

i mean watz da answer for that question????

These are the answers
Steps
measure a measuring cylinder.
Decant the saturated solution in order to make sure that no extra salt is there.
note down the volume of water
as density of water is 1g/cm3 hence mass of water is also same as its volume (in cm3)
after that remeasure the cylinder and note the new mass
from the new mass measure subtract the mass of cylinder and water
what ever left is the mass of salt in soultion.

part B
then use unitary method to find the solubility i.e.
if x mass of solvent is dissolved completely in y volume of water at 60 °C then
how much mass is soluble in 1l i.e. 1 dm3 or 1000cm3.

as i dont have the soultion so i cant perfoam them is it practical or theory??? :O:

 

[filza94]

okay thanks i got it......bt can u solve one quetion here in dix topic viewtopic.php?f=26&t=6455&p=63755#p63755 itx for O/N 2009 JUX GO N C N HELP IN ANSWERING IT.....