Biology; Chemistry; Physics: Post your doubts here!

[black widow]

can someone tell me how exactly is the time period of a pendulum inversely proportional to the gravitational field strength?

 

[Nabeel.Ahmad]

can someone tell me how exactly is the time period of a pendulum inversely proportional to the gravitational field strength?

The greater the gravitational strength, the greater the weight, and the faster it will accelerate when dropped, while being suspended to a string. So it will complete its oscillation in shorter time.
So GRAVITATIONAL FIELD STRENGTH is INVERSELY PROPORTIONAL to Time Period.
The lesser the value of g, the greater the Time Period.
The more the value of g, the lesser the Time Period.

 

[***amd***]

can someone tell me how exactly is the time period of a pendulum inversely proportional to the gravitational field strength?

--> the stronger the gravitational field, the sooner will the pendulum come down when it starts going up. that means, it will take less time to complete its movement, as it'll have to go less higher to the sides.

 

[asadalam]

Can someone give a detailed explanation about ways of obtaining salts,both soluble and insoluble,especially titration?

 

[Nabeel.Ahmad]

Can someone give a detailed explanation about ways of obtaining salts,both soluble and insoluble,especially titration?

When you mix two soluble solutions, together, there might be an insoluble precipitate formed. You just filter it, and collect it.

But if a soluble salt forms, you just have to heat the solution, and evaporate some of the water, and then allow it to call, and cystals of that salt will appear. You collect them.

 

[asadalam]

When you mix two soluble solutions, together, there might be an insoluble precipitate formed. You just filter it, and collect it.

But if a soluble salt forms, you just have to heat the solution, and evaporate some of the water, and then allow it to call, and cystals of that salt will appear. You collect them.

I knew that much,details de yar,regarding titration

 

[black widow]

--> the stronger the gravitational field, the sooner will the pendulum come down when it starts going up. that means, it will take less time to complete its movement, as it'll have to go less higher to the sides.

thnx yar

 

[black widow]

asadalam
But if a soluble salt forms, you just have to heat the solution, and evaporate some of the water, and then allow it to call, and cystals of that salt will appear. You collect them.[/quote]
it is a very long topic
in the thread for IGCSE, i have explained the reactivity series for the method, u can view it from there
also do go through salt section of these notes, it will be very helpful

 

[Nabeel.Ahmad]

I knew that much,details de yar,regarding titration

What are Chemists?
What is CHEMISTRY?
It's the study of matter. Elements. Compounds. Salts.
Chemists work in the laboratory, dealing with compounds. Dealing with natures elements, their chemical composition.

Nature has provided us with a number of elements. The periodic table is full of them.
Now look, they all have different structures. Different number of protons. Neutrons. Electrons.
Electrons orbit around the Nucleus?
Why? Because they are attracted to the Nucleus.
Now you'll say why don't protons orbit around the Electron? That's because Electrons are 1836 times lighter than Protons.
That difference in mass forced the electrons to orbit around the positively charged nucleus, in different energy levels called shells.

Now coming to the point.
Different elements form different compounds.
You're sitting in front of a computer breathing air. You're inhaling Carbon Dioxide. That is a compound.

But not all elements, like Carbon Dioxide, are found in nature.
Some need to be formed in the laboratory.

So Chemists, take different compounds, and react them together to make new compounds.
One of the methods used by Chemists is called TITRATION!

Titration is of several types. Redox Titration. Acid-Base Titration.

The basic theme is that you are supposed to add a known volume of an acid, into a known volume of an alkali, and then completely neutralize it.
You add an indicator into the Alkali, and keep adding the acid until the indicator changed color, which it will whenever the solution transitions from an Alkali to an acid.
So the point, when the color changes, is called the END POINT of that specific titration. Now, you will then look at the burette, through an angle of 90 degrees, to avoid parallax error, and then record the amount of acid you used to neutralize that alkali, which was in the titration flask, placed below the burette.

Using these volumes, you can find out different concentrations, moles and stuff. Calculate.
First you performed the TITRATION. Then you got the values, so you calculated the missing variables.
That is what you do in ALTERNATE TO PRACTICAL. You get a question about TITRATION, and it has different values, you work on it.

Now, coming to your problem about SALTS.
There are soluble salts, and insoluble salts.
Insoluble are made by precipitation.

Soluble salts are made by neutralization, or some other reactions. When you add SODIUM HYDROXIDE to HYDROCHLORIC ACID, the solution will become neutral. The Hydroxide ions will combine with the Hydrogen ions to give a water molecule. And a salt will be formed. Now that is a SOLUBLE SALT.

HOW DO YOU COLLECT IT?

You heat it, and then allow it to cool. This is called CRYSTALLIZATION. You studied this in CHAPTER 2; Purification of substances. How to collect a soluble salt from a solution.

But if an insoluble precipitate like Barium Sulphate settles at the bottom of the beaker. How do you collect it?
You studied that in CHAPTER 2, as well. You are supposed to grab a filter paper, and pass the solution through it, and the insoluble precipitate will be collected as a RESIDUE. The thing you get on the filter paper.

 

[asadalam]

Thanks amigos

 

[funky brat]

Which paper has been the toughest for Physics in the last ten years?

 

[black widow]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Physics%20(5054)/5054_s04_qp_1.pdf
can someone explain question no. 31. The answer is B, whereas i chose A
with the left hand rule, i get A, and with the right hand rule, i get B
so exactly what rule am i supposed to use and why?
shouldnt i suppose that the beam of electrons is like a current carying wire and then use the left hand rule?

 

[Faizan Muhammmad]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20O%20Level/Physics%20(5054)/5054_s04_qp_1.pdf
can someone explain question no. 31. The answer is B, whereas i chose A
with the left hand rule, i get A, and with the right hand rule, i get B
so exactly what rule am i supposed to use and why?
shouldnt i suppose that the beam of electrons is like a current carying wire and then use the left hand rule?

in current carrying wire question we assume conventional current which is flow of positive charges
this is flow of negative so RHR will be used

 

[black widow]

in current carrying wire question we assume conventional current which is flow of positive charges
this is flow of negative so RHR will be used

thnx

 

[black widow]

are homogenous and heterogenous mixtures included in the syllabus of O Level Chemistry?

 

[Nabeel.Ahmad]

are homogenous and heterogenous mixtures included in the syllabus of O Level Chemistry?

I don't think so.

 

[Nabeel.Ahmad]

black widow

How to prepare ATP of Chemistry, Biology and Physics?

I'll read the book, and understand all the concepts. And that will enable me to do Paper 1 and Paper 2 effectively.
What about ATP? How to prepare that? Is there like a specific pattern for it?
Is it easy or hard? Compared to other papers?

 

[black widow]

black widow

How to prepare ATP of Chemistry, Biology and Physics?

I'll read the book, and understand all the concepts. And that will enable me to do Paper 1 and Paper 2 effectively.
What about ATP? How to prepare that? Is there like a specific pattern for it?
Is it easy or hard? Compared to other papers?

ATP is easiest paper of all
for Chemistry, the questions are like repeated the whole time, with practice u can master them. u need to be a 'master' at Speed of Reactions, Moles, Identification of Ions, and Acids and Bases. When u solve past papers, most of the questions are repeated
for Bio, the questions are new and change frequently apart from the magnification one. it can be solved easily if u have good knowledge of the book and UNDERSTANDING
for phy, i haven't actually started them so i can't guide u on that. sorry

 

[dora the explorer]

Assalamualaikum Wr Wb...
Can someone please tell me what total transfer is? How to calculate it? etc...

 

[Eimaan Aamir]

I'm appearing for biology privately and without any tutor, so can someone give me any tips on the theory? I can solve the ATP really good except magnification, so can someone help me with that?