Biology; Chemistry; Physics: Post your doubts here!

[usama321]

I'm horrible at paint but I hope you get the idea:

View attachment 29459

The red lines represent the NORMAL (90 deg.) to the Mirror. First of all draw the normal at the point where the incident ray strikes the mirror. Then measure the angle of incidence and draw the reflected line. Remember angle of incidence = angle of reflection. Do the same for the second light ray as well. The coloured angles represent equal angles.
The black dotted lines show the method for tracing back the image of P. Just trace back the reflected rays using dotted lines BEHIND the mirror and the intersection of the dotted lines is the image of P represent by P'.
To verify the image of P, you can use the distance method represented by the pink line. The distance of P from mirror = The distance of P' from mirror. This holds true for all plane mirrors.
P.S. The drawing is not accurate nor neat.

couldn't help lol ing at it

 

[Saad Mughal]

couldn't help lol ing at it

-_-

 

[irfan.kheerdali]

-_-

https://www.xtremepapers.com/community/threads/o-level-notes-center.11138/
Press F3 and type 'Chemistry'.

thanks very much

 

[Deadly Orchid]

I'm horrible at paint but I hope you get the idea:

View attachment 29459

The red lines represent the NORMAL (90 deg.) to the Mirror. First of all draw the normal at the point where the incident ray strikes the mirror. Then measure the angle of incidence and draw the reflected line. Remember angle of incidence = angle of reflection. Do the same for the second light ray as well. The coloured angles represent equal angles.
The black dotted lines show the method for tracing back the image of P. Just trace back the reflected rays using dotted lines BEHIND the mirror and the intersection of the dotted lines is the image of P represent by P'.
To verify the image of P, you can use the distance method represented by the pink line. The distance of P from mirror = The distance of P' from mirror. This holds true for all plane mirrors.
P.S. The drawing is not accurate nor neat.

Wow, thank-you.

 

[Saad Mughal]

Wow, thank-you.

 

[irfan.kheerdali]

all types of questions in biology p2 qu.9,10 (the 2 last question) ?? and how to answer it

 

[irfan.kheerdali]

biology p21 qu.2(c) and 2(d) 2011

 

[genius.student]

hi,guys !!!!!!!!! i'm in a great dilemma whether to appear with bio or not ...i'm a private candidate and will be appearing in oct/nov 2013 ...this is going to be my first attempt and i'm ready to give my Islamiyat and Urdu ..but not prepared for the 3rd subject ..i have approx 3 months for preparation ..should i start preparing bio or p.st ??? which is more suitable for this short time ???kindly help me out!!i'll be very thankfull

 

[AbbbbY]

hi,guys !!!!!!!!! i'm in a great dilemma whether to appear with bio or not ...i'm a private candidate and will be appearing in oct/nov 2013 ...this is going to be my first attempt and i'm ready to give my Islamiyat and Urdu ..but not prepared for the 3rd subject ..i have approx 3 months for preparation ..should i start preparing bio or p.st ??? which is more suitable for this short time ???kindly help me out!!i'll be very thankfull

From scratch, in that sort of time, you can do both. However I'll suggest Pak Studies for now.

 

[Hassan Abdullah123]

i m confused while attemting theory section can any 1 help

 

[Hassan Abdullah123]

actually i cannot judge that what should be wrriten in order to get full marks

 

[Happily Insane]

actually i cannot judge that what should be wrriten in order to get full marks

You might want to check the mark schemes. They contain complete answers and will surely give you an idea.

 

[Aly Emran]

actually i cannot judge that what should be wrriten in order to get full marks

You might want to check the mark schemes. They contain complete answers and will surely give you an idea.

Happily Insane's right(woh what a name ) u'll get points for ur answers like 2 marks would require 2 points and so on! for phy and chem (maybe bio) a lot of questions r repeated so if u see a question and u know the answer i would advice look in mark scheme for the top answers and learn them by heart! Trust me this works but dont look for answers first, try solve it by urself first hope i helped

 

[Hassan Abdullah123]

thnx

Happily Insane's right(woh what a name ) u'll get points for ur answers like 2 marks would require 2 points and so on! for phy and chem (maybe bio) a lot of questions r repeated so if u see a question and u know the answer i would advice look in mark scheme for the top answers and learn them by heart! Trust me this works but dont look for answers first, try solve it by urself first hope i helped

 

[Salman Shah Jee]

Hye!I have given 3 papers in M/J and now i want to give the remaining with some additional subjects like (PHYSICS,BIOLOGY)5125,URDU B,AND HUMAN AND SOCIAL BIOLOGY in 2014 May/june..Cambridge will not let me to give biology paper along with (physics,biology)and human and social biology So should I quit one of these three and give one of them in the upcomming oct/nov or extend my olevel period till 2014 oct/nov.Its urgent please heeeeeeeeeeeelllllllpppppppppppppppppppppppppp

 

[Salman Shah Jee]

Hye!I have given 3 papers in M/J and now i want to give the remaining with some additional subjects like (PHYSICS,BIOLOGY)5125,URDU B,AND HUMAN AND SOCIAL BIOLOGY in 2014 May/june..Cambridge will not let me to give biology paper along with (physics,biology)and human and social biology So should I quit one of these three and give one of them in the upcomming oct/nov or extend my olevel period till 2014 oct/nov I want to become a doctor actually thats why i am interested in bio.
.Its urgent please heeeeeeeeeeeelllllllpppppppppppppppppppppppppp

 

[AbbbbY]

actually i cannot judge that what should be wrriten in order to get full marks

For starters, you'll need to ensure you don't fill the lines with heaps of useless crap.

Your answers need to be precise, to the point. D0n't fill in answering the Class 2 way.

Question: Why is Flourine more reactive than Chlorine?
Answer: F has lesser total no. of e- than Cl hence its protons are relatively more exposed leading to higher reactivity than Cl.
Don't Answer: Flourine is more reactive than Chlorine because Flourine has less electrons than Chlorine. Due to this, the protons in Flourine are more exposed and can attract electrons more readily than Chlorine

You'll get the mark either way. But, you'll waste way too much time, space and energy. Get my drift?


Write less, write wise.
You get the marks, mostly, due to keywords/steps depending on the question. If you include them while maintaining sub-proper sentence structure, you'll get the mark.

 

[AbbbbY]

a lot of questions r repeated so if u see a question and u know the answer i would advice look in mark scheme for the top answers and learn them by heart! Trust me this works but dont look for answers first, try solve it by urself first hope i helped

Don't mind me saying, but this method can backfire.

Psychological research shows that the human brain, when under the time and pressure of an exam (cannot be replicated at home under any circumstances) tends to make up things to fill the gaps, be delusional and fabricate things to suit its needs. Such a method can backfire because the brain can remember only so much past answers by heart.
What if they've twisted one tiny detail?
My advice would be to do it the right way; through the proper channel.

You don't just need the A/A*, you also need to know what's being taught for the future. If you use shortcuts (especially in Math), they'll come back to haunt you at A Levels and above. Seen many examples of this in real life to say this on a public forum. Do that if you're fairly certain you won't be using that in life in future (eg. I left Section 3 in History, because, well, I could, and saw no real purpose of it for my life + future in general. Do I have any regrets? Yes. I do. To make up for that and be historically subsound, I'm spending a majority of my spare time reading up on Pakistan's history post 47' in depth. Just saying)

(Although, O Level Chem ATP moles questions are usually like 0.000234, 0.00234, 0.00234/0.00468/0.00117, 0.0234 etc. Well, at least that's how it was in my time)

Edit: Oops. Just saw the last line. Hahah

 

[Neil Shah]

Can someone tell me how to answer question 8 in the attached file (o level nov 04)

 

[Nabeel.Ahmad]

Can someone tell me how to answer question 8 in the attached file (o level nov 04)

The total mass of the load and the wheelbarrow = 60kg.
Weight of Load and wheelbarrow = Mass x Gravitational Field Strength
= 60 kg x 10 N/kg
= 600 N

The Clockwise Moment generated by this weight along Pivot = Force x Distance from Pivot
= 600 N x 70 cm
= 42000 Ncm

So, In order to lift the load and the wheelbarrow an Anti-Clockwise moment of the same magnitude is needed.

Clockwise Moment = Anti-Clockwise Moment.
42000 Ncm = F x (70cm + 50cm)

F = 42000/120
= 350 N

So a force of 350 N needs to be applied to produce an Anti-Clockwise moment of 42000 Ncm along the pivot, in order to lift the wheelbarrow and the load.

 

[Neil Shah]

Thank u so much Nabeel Ahmed and Aly Emran !!!