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Physics, Chemistry and Biology: Post your doubts here!

ZaqZainab

ZaqZainab

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Mohammed salik said:
Guys a Question plz: http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s12_qp_31.pdf Q11 b! In Gap A why cant u PuT Light Dependendant Resistor! Why should we put on Only in Gap B! Any Help Would Be Helpful, Thanx IN ADVANCE!!
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11 b Because it is NPN transistor the current flow is from emitter to base and here you DON'T need a thermistor (This is for temperatures and here we don't have to note the temperature) Your question why don't we keep Variable resistor at b and LDR at A this has a lot to explain but lemme give it a go so when the light intensity decreases(becomes dark) the resistance increases for LDR and now when Resistance increases Voltage increases and we need a higher share of voltage at B not at A because we need the PD across the Base to e larger enough for the base current to switch on the collector-emitter current as when the large current flows from the collector to emitter the bulb will light and at A is has Less share of resistance from the power supply.
 
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Ramzaa

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hey people where can we get the old past papers like m/j 2000??
please tell me i really need themm..:)
 
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himanshu dave

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semsemhosam said:
Assalam-o-Alaikum.
Post your Physics, Chemistry and Biology doubts in here and members, along with me will try their best to help you out. :)
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in electrolysis a compound is given a charge of 0.48 A first then they chnge it to 0.24 A in experiment 2 state what happens in terms of ions, electrons, and atoms and also what happens to the amount of H+ IONS
 
ZaqZainab

ZaqZainab

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tweetie said:
please help me asap for biology paper 1
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Biology (0610)/0610_s12_qp_12.pdf
q8, q13, q16, q20, q28 and q40....please explain me the answers
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8 is retraction obviously it needs more energy like when you run your leg muscles contract so you need more oxygen you see how fast you breath.the one leaving without contraction is 6 so it is suppose to be less! which is the only option 40
13 Lipase produced in the pancreas and secreted into the small intestines through pancreas so duodenum is nearest to the pancreas so yeah that's why it is the most
16 you have to lean this that the walls of the LEFT OF THE HEART(right of yours which is Q) are thicker than the RIGHT SIDE OF THE HEART
20 yeast produces CO2 in the absence of Oxygen that's what makes the break rise. the term used is aerobic which means breathing in the absence of oxygen
40 the river is flowing with out any change then adding the sewage decreases the oxygen and increase the mineral ions this is done only at the starting and then you see the levels come back to normal
I hope i helped
 
ZaqZainab

ZaqZainab

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Kaulish Mehta said:
hey i was solving a chemistry paper, and had this doubt:
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s11_qp_32.pdf
question number: 3 a (ii)
I know the answer ( through the marking scheme ofcorse), but i am yet not able to figure out how to solve it
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have a look at the volume of thiosulfate 50 and 25
two time of 25 is 50 so 25*2 is 50
look at there time now 48 and 96
double of 48 is 96 so 48*2=96
Now at 40 and 10
four times 10 is 40 that is 10*4 is 40
so 60*4 will give you your answer
I hope i helped
 
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