Biology; Chemistry; Physics: Post your doubts here!

[Talha Farooqui BSS]

cann u plz help me in preparing atp of bio

 

[black widow]

All ions migrate.
Cations migrate to the cathode.
Anions migrate to Anode.

It's the deposition which counts.
Don't mix MIGRATING And DEPOSITION.
OH- and Cl- both migrate to ANODE.
But CHLORIDE ION gets deposited if the solution is concentrated.


And yes, the anions should be concentrated.
The ANION is always concentrated in Concentrated solutions.
If they mention ''Dilute''.. then you have to deposit the OH- Ion.
But if they say CONCENTRATED or they don't mention anything, than you have to assume it's concentrated.

only metals can deposit as the ions can turn back to metal at the cathode. Non-metals are NOT deposited
for example in electrolysing conc aqueous CuCl2 using inert electrodes, the reaction for the cathode will be
Cu+2 (aq) + 2e- ------> 2Cu (s)

for the anode it will be
2Cl- (aq) ----------> Cl2 (g) + 2e-

Cl2 is discharged as it is in a higher conc and because the Cl- ions give up electrons more readily than OH- ions do IN THIS CONC SOLUTION.
Cl2 is a gas at room temp and pressure
deposition refers to only metals as they are solids at room temp and pressure (except mercury. mercury is a liquid at room temp and pressure)
at the anode Cl- ions form molecules and become Cl2 gas

(notes. in conc solutions only the halogens will be discharged at the anode instead of OH-)
the halogens are the group 7 elements
SO4- cannot be discharged

 

[ZohaKhan]

is biology matters ok for bio or jones mary????

 

[snowbrood]

Someone pleaase help!
http://papers.xtremepapers.com/CIE/Cambridge International O Level/Physics (5054)/5054_s08_qp_1.pdf
Question 30, the answer is B, but how is it possible? Could you give an explanation?

X is highest resistance as the resistors are all in series so they add up high resistance less current .in y there is a parallel arrangement so resistance is lowest less resistance high current

 

[Ruman Wajih]

What is meant by Thinking Distance and Breaking Distance. (Kinematics)

 

[Nabeel.Ahmad]

What is meant by Thinking Distance and Breaking Distance. (Kinematics)

Thinking distance is the distance traveled by the vehicle when the driver is thinking about braking.
Breaking distance is the distance traveled by the vehicle when the brakes are being applied, till it comes to rest.

 

[annorel]

can I have notes for renewable and non renwable resources in geography

 

[Nabeel.Ahmad]

can I have notes for renewable and non renwable resources in geography

https://www.xtremepapers.com/community/threads/o-level-notes-center.11138/

 

[annorel]

https://www.xtremepapers.com/community/threads/o-level-notes-center.11138/

thanks

 

[Qasim Hafeez]

How to find formula for 2 elements's reaction?

 

[Nabeel.Ahmad]

How to find formula for 2 elements's reaction?

Hydrogen and Oxygen react to form Water.
Nitrogen and Hydrogen react to form Ammonia.

There are different formulas. You just need to learn them.

 

[Qasim Hafeez]

Hydrogen and Oxygen react to form Water.
Nitrogen and Hydrogen react to form Ammonia.

There are different formulas. You just need to learn them.

Many other element also react together how find their formula?

 

[Nabeel.Ahmad]

Many other element also react together how find their formula?

Many reacts take place on earth.
They are not always between ''Elements''.
Compounds react with Elements. Compounds react with other compounds.
In order to find the formula of an ionic compound formed between two elements.
You just swap their valencies.
Like Na+1 and Cl-1
Forms NaCl.

Mg+2 and O-2
Swapping them, we get Mg2O2.. which can be simplified and written as MgO. (Magnesium oxide, which has a melting point of 2800 and is used as refractory material for blast furnaces)

This is only for ionic compounds.
For covalent, you have to learn the formula.
H2O is the universal formula of water.
CO2 is the universal formula of Carbon Dioxide.
CO is for Carbon Monoxide. You need to learn these, look at their structures, their bonding and understand it and that's the formula.

 

[Qasim Hafeez]

Many reacts take place on earth.
They are not always between ''Elements''.
Compounds react with Elements. Compounds react with other compounds.
In order to find the formula of an ionic compound formed between two elements.
You just swap their valencies.
Like Na+1 and Cl-1
Forms NaCl.

Mg+2 and O-2
Swapping them, we get Mg2O2.. which can be simplified and written as MgO. (Magnesium oxide, which has a melting point of 2800 and is used as refractory material for blast furnaces)

This is only for ionic compounds.
For covalent, you have to learn the formula.
H2O is the universal formula of water.
CO2 is the universal formula of Carbon Dioxide.
CO is for Carbon Monoxide. You need to learn these, look at their structures, their bonding and understand it and that's the formula.

In some formula in book, there is 2K reacting with some elements?
Why there is a 2 in it? Potassium symbol is only K.

 

[annorel]

How to find formula for 2 elements's reaction?

2 is written to balance the equation

 

[annorel]

tell me the equation I will explain

 

[Nabeel.Ahmad]

In some formula in book, there is 2K reacting with some elements?
Why there is a 2 in it? Potassium symbol is only K.

2 moles of Potassium are reacting.
But it should be read as Potassium.
It's just that after balancing these numbers are adding to the formulas.

 

[Qasim Hafeez]

Cl2 + 2kBR

 

[annorel]

Cl2 + 2kBR

cl2 means 2atoms of chlorine
2atoms of chlorine needs 2 electrons
and 1k or 1br can provide just 1 electron to chlorine
2 is written to make 2 atoms of br or k react with 2 atoms of chlorine

 

[annorel]

is it fine now?