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Physics, Chemistry and Biology: Post your doubts here!

Tekno-M

Tekno-M

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There are questions that keeps coming every paper which I can't seem to get right in Physics Paper 6.

1. What are the common causes for error in an experiment ?
2. How to improve reliability ?
3. Variables that should be kept constant when repeating an experiment.

Anyone care to lend a hand ?
 
thats_me

thats_me

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Tekno-M said:
There are questions that keeps coming every paper which I can't seem to get right in Physics Paper 6.

1. What are the common causes for error in an experiment ?
2. How to improve reliability ?
3. Variables that should be kept constant when repeating an experiment.

Anyone care to lend a hand ?
Click to expand...
All of the 3 depend on the question ur dealing with
http://www.xtremepapers.com/community/threads/amazing-notes-for-physics-paper-6.16788/
Try reading these i found them very helpful :)
If any specific ques u can ask them i'll try helpin if i can :)
 
M

*MK*skydiver :D

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Thanks a bunch !
but in 5c ,,whats exactly is " mark" it ? how would the diagram look lyk ?? thanks again :D
thats_me said:
2d: the question is for 2 marks so just tick 2 most appropriate ones..
the "zig zag" thingy u need to break the graph
5d: Yep! its correct
5c: It means to mark two fixed points for measurement, so attach theses marks at both the ends of the spring and then get a ruler and measure by placing it near
No, th last one i guess u have to place the testube between the two blocks and using a clamp or sumthing place a ruler near to it and measure
Click to expand...
 
S

Stormcry72

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NIM said:
(i) lithium oxide + sulphuric acid lithium sulphate + water. Change into a symbol equation???

(ii) CuO + 2H*___ Cu2* + H2O. Change the ionic equation into a symbol equation???

(iii) Carbonyl chloride reacts with water to form two acidic compounds. Suggest which acidic compounds are formed (any 3)???

(iv)) Using 25.0 cm3 of aqueous sodium hydroxide, 2.24 mol / dm3, 3.86 g of crystals were
obtained. Calculate the percentage yield.
2NaOH + H2SO4 Na2SO4 + 2H2O
Na2SO4 + 10H2O Na2SO4.10H2O
Number of moles of NaOH used = ???
Maximum number of moles of Na2SO4.10H2O that could be formed = ???
Mass of one mole of Na2SO4.10H2O = 322g
Maximum yield of sodium sulphate-10-water = ??? g
Percentage yield =??? %
help me guyz!!!
:D
Click to expand...
i) Li2O + H2SO4 -----> Li2SO4 + H2O

ii) CuO + 2HCl ------> CuCl2 + H2O

iii) No. of moles of NaOH= concentration * volume = 2.24*0.025 = 00.056
Max No. of moles of Na2SO4.10H2O formed= (do the molar ratio, in this case NaOH : Na2SO4 = 2:1) therefore no. of moles of Na2SO4.10H2O = 0.056/2 = 0.028
Max yield = no. of moles * Mr = 0.028*322 = 9.016
percentage yield = (actual mass obtained/calculated mass)*100
= (3.86/9.016)*100
=42.8%

hope it helped :)
 
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Tekno-M

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kainat husain

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thats_me said:
1d : the height is between 2mm to 3mm you have to estimate it ur self & lenght and width are same as the card so use the values frm (1bi-->l & w)
q3: v: Now u can c the line with end poits E & F right? extend that line to CD <This line should the same lenght as b (the ans for part(iv)) at the end of this line mark the point 'I'
vi: Here u have to join the point that u just name 'I' with the normal and mark that point 'J' ( such that <FIJ forms a right angled triangle)
5a: Using a set square , keep it perpendicular to the metre rule and c if its horizontal to the surface..
Click to expand...
thank u soo much! but for q3..i knw we have to draw for same length but wen i drew for same length it didnt reach to the line 'CD'
 
thats_me

thats_me

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kainat husain said:
thank u soo much! but for q3..i knw we have to draw for same length but wen i drew for same length it didnt reach to the line 'CD'
Click to expand...
hun the question doesnot ask us to extend to CD , u r correct now for the next part join the end of this line to the normal (NN')
 
areebaization

areebaization

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kainat husain said:
thank you sooooo very much dear it really helped JAZAK ALLAH KHAIRAN!
but i even wanna knw the drawin for 2a! it would b really better if u can show the drawin
http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s06_qp_6.pdf
in this q1d how will v knw the length and breadth and height dear? :/ like how ill v get the volume?
q5 a how will we draw|? like how to cheak if its horizontal!? :/
and q3 vi- how should v draw tht line :/
thank you
Click to expand...
Q 2a) http://www.mediafire.com/i/?tlmavyawwhz811q
Q1 d) We'll have to take the L and H from 1.1 (coz it says so in the question) and we'll have to take y as 2.5 mm coz its the average of the two given possibilities for y.
Answer: 58 mm x 60 mm x 2.5mm = 8.7 milliliters
Q3 vi) Draw a line 90 degree to NN'. Just like you draw a normal.
Q5 a) Take another ruler make sure that the ends of it touch the bench (To ensure correct output) then measure both ends of the original meter rule. If the result of both measurements is same they're horizontal.


i
 
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