Biology; Chemistry; Physics: Post your doubts here!

[exploded diper]

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The test tube must be dry because any water or chemicals in the test tube may affect the experiment and consequently the result
Ethanol emulsifies fats (fats are soluble in ethanol). If we added water first, then there would be no reaction. When the lipids dissolve in ethanol, they will precipitate in water

ohkay..........thx

 

[syeda salka hashmi]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Chemistry (5070)/5070_s08_qp_1.pdf
question 38...answer plz.. and explain thoroughly

B as there are two carbon to carbon double bond!

 

[syeda salka hashmi]

How exactly is the answer D. A detailed explanation would be appreciated
View attachment 39229

are these answers correct?

 

[Awesome12]

are these answers correct?

Yes

 

[syeda salka hashmi]

Yes

aite

 

[funky brat]

How exactly is the answer D. A detailed explanation would be appreciated
View attachment 39229

Alkalis react with ammonium salts to give off ammonia gas. The first 3 are basic oxides so D's the answer.

 

[Awesome12]

Alkalis react with ammonium salts to give off ammonia gas. The first 3 are basic oxides so D's the answer.

Thanks, but its quite an old post, and I already got the answer

btw. here are the star notes
Note on star formation
If there is any problem regarding the visual display of text, do tell me; i will type it again

 

[funky brat]

Thanks, but its quite an old post, and I already got the answer

btw. here are the star notes
Note on star formation
If there is any problem regarding the visual display of text, do tell me; i will type it again

Some words are blurred, I'll ask you if I need verification. Thanks a lot.

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_qp_21.pdf
Question no. 3 (a) (i)
How do we draw all the junctions and voltmeter?

 

[DaniyalK]

Can somebody explain the concept behind this one?

 

[funky brat]

Can somebody explain the concept behind this one?

This is the refraction part. In deeper water the wavelength is longer whereas is shallow water the wavelength becomes shorter. And when a ray moves from a denser (deeper water) to rare medium (shallow water) it bends away from the normal.

 

[Awesome12]

Can somebody explain the concept behind this one?

A deep region is a less dense region and a shallow region is a denser region
When the wave passes from a less dense to a denser region, it refracts towards the normal and its wavelength decreases

 

[funky brat]

http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_w11_qp_21.pdf
Question no. 3 (a) (i)
How do we draw all the junctions and voltmeter?

Ignore my poor drawing skills.

 

[Awesome12]

Ignore my poor drawing skills.

No problem thanks

 

[exploded diper]

how is the ans of b(111)b; (-13,2)

 

[Awesome12]

How is the answer B?

 

[Karim Nabil]

How is the answer B?

View attachment 40324

here you will use the idea of combined resistance
now calculate the combined resistance in a parallel circuit
r1*r2/r1+r2
3*3/3+3=1.5 ohm
then at series circuit
R1+R2+R3.....
now 1.5+4.5=6 ohm
this is total resistance b/w X and Y
for this we have to close all switches so i don't think it is a B, it is A
anyways which year is it so i'll check the m.s

 

[FLRNAB]

here you will use the idea of combined resistance
now calculate the combined resistance in a parallel circuit
r1*r2/r1+r2
3*3/3+3=1.5 ohm
then at series circuit
R1+R2+R3.....
now 1.5+4.5=6 ohm
this is total resistance b/w X and Y
for this we have to close all switches so i don't think it is a B, it is A
anyways which year is it so i'll check the m.s

If S3 is closed the current will bypass 4.5 ohm resistor so resistance b/t X and Y will fall to 1.5 ohm.

 

[DaniyalK]

You need to enlarge the point (8,2) from center (1,2). Count the number of units from the center to (8,2). It's +7. Multiply that by the scale factor, -2 and you get -14. This means you move 14 units to the left from the center, which gives you (-13,2)

 

[Awesome12]

here you will use the idea of combined resistance
now calculate the combined resistance in a parallel circuit
r1*r2/r1+r2
3*3/3+3=1.5 ohm
then at series circuit
R1+R2+R3.....
now 1.5+4.5=6 ohm
this is total resistance b/w X and Y
for this we have to close all switches so i don't think it is a B, it is A
anyways which year is it so i'll check the m.s

I know that method. That is the method I used to get the answer but I was also getting A. I checked the marking scheme and it says B
It is oct/nov 2013 p11