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What do u think A grade for bio P31 will be from out of 40 ???
And what did ur teachers say about threshold of bio 31 june 2011 ???
And what did ur teachers say about threshold of bio 31 june 2011 ???
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Threshold of Bio AS practical P31 ?!
- Thread starter Romeo10
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http://notezone.net/cambridgechem/chemi ... sis%5D.pdf plz go dix link pg 11 n c answers below of it
First of all you need the mass of FA1. In the first table you have the mass of the empty test tube and the
mass of the test tube + FA1. All you do is subtract the values 12.80 - 10.50 giving you 2.30g of FA1.
In the second table you need the mass of FA1 after heating. Again, you just subtract the values 11.76 -
10.50 = 1.26g FA1 after heating.
1 d. (i) The mass of anhydrous XS04 present in the crystals is what is left over after heating = 1.26g
1 d. (ii) The mass of water driven from the crystals is the loss in mass that has occurred when the FA1 was
heated. Before heating there were 2.30g of FA1 and after heating there were 1.26g. So the mass of water
lost is 2.30 - 1.26 = 1.04g
1 e. To calculate the number of moles of water in the sample of FA1 you use the formula no. of moles =
mass/mass of 1 mole which gives you 1.04/18 = 0.058 mol
1 f. The number of moles in XSO4
7 moles of H20 gives 1 mole XSO4 (from the formula XSO4.7H20)
So 0.058 moles of water give 0.058/7 = 8.29 x 10 ^ -3 moles of XSO4
1 g. To calculate the relative formula mass of XSO4 you use the formula mass of 1 mole = mass/no. of
moles which gives you 1.26/8.29 x 10 ^ -3 = 152.7
1 h. To calculate the Ar of element X you first find the Mr of SO4 which is 32 + (4 x 16) = 96
You subtract this from the RFM from part g giving you 152.7 - 96 = 56.7
First of all you need the mass of FA1. In the first table you have the mass of the empty test tube and the
mass of the test tube + FA1. All you do is subtract the values 12.80 - 10.50 giving you 2.30g of FA1.
In the second table you need the mass of FA1 after heating. Again, you just subtract the values 11.76 -
10.50 = 1.26g FA1 after heating.
1 d. (i) The mass of anhydrous XS04 present in the crystals is what is left over after heating = 1.26g
1 d. (ii) The mass of water driven from the crystals is the loss in mass that has occurred when the FA1 was
heated. Before heating there were 2.30g of FA1 and after heating there were 1.26g. So the mass of water
lost is 2.30 - 1.26 = 1.04g
1 e. To calculate the number of moles of water in the sample of FA1 you use the formula no. of moles =
mass/mass of 1 mole which gives you 1.04/18 = 0.058 mol
1 f. The number of moles in XSO4
7 moles of H20 gives 1 mole XSO4 (from the formula XSO4.7H20)
So 0.058 moles of water give 0.058/7 = 8.29 x 10 ^ -3 moles of XSO4
1 g. To calculate the relative formula mass of XSO4 you use the formula mass of 1 mole = mass/no. of
moles which gives you 1.26/8.29 x 10 ^ -3 = 152.7
1 h. To calculate the Ar of element X you first find the Mr of SO4 which is 32 + (4 x 16) = 96
You subtract this from the RFM from part g giving you 152.7 - 96 = 56.7
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27/40 ........ I just wanted to check for this mark .... Because the threshold should be and must be very lowwww !!
Any1 ... His teacher told him anything about the threshold of bio p31 june 2011 .... Plz share here !!!
Any1 ... His teacher told him anything about the threshold of bio p31 june 2011 .... Plz share here !!!
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Yeah I asked my teacher he said that it'll be 30 or abv. 
- Messages
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It must be very low especially for bio 31 as it was very hardddd !
As my teacher said that it will be 27/40 and other teacher said 33/40 ??
So check that is for BIO/31 not other variants .....
As my teacher said that it will be 27/40 and other teacher said 33/40 ??
So check that is for BIO/31 not other variants .....
Topic To Stress On Biology Paper 33 AS
Gaseous exchange
Infectious diseases
Immunity
Transport: In plants- all the pathways in the cell (apoplast n symplast)
in humans- cardiac cycle, pressure graph, etc...
Nitrogen cycle
Itx surely cuming as my Biology Teacher predicted them every year she does n it cumss last year 4 my O level also she predict so i got A* n dat all camee now she precdicted for AS Paper 33 so evryone study all topics anyway so focusing on these shouldn't make u forget the others!!!!
Gaseous exchange
Infectious diseases
Immunity
Transport: In plants- all the pathways in the cell (apoplast n symplast)
in humans- cardiac cycle, pressure graph, etc...
Nitrogen cycle
Itx surely cuming as my Biology Teacher predicted them every year she does n it cumss last year 4 my O level also she predict so i got A* n dat all camee now she precdicted for AS Paper 33 so evryone study all topics anyway so focusing on these shouldn't make u forget the others!!!!