Physics, Chemistry and Biology: Post your doubts here!

[Ameena Eesa]

Do birds have waterproof feathers or oil glands which prevents their feathers from absorbing the water

Sis, the oil glands are to lubricate the feathers. The uropygial gland secretes the oils. This gland is found near the base of the tail and produces an oily substance that contains diester waxes that help waterproof feathers and keep them flexible. Birds will spread this oil to each feather.

Actually, it's like most people believe that birds waterproof their feathers by the oil located on their backs but that is not how they waterproof it. The interlocking hooks and barbules on feathers is what makes a bird waterproof and not all bird are waterproof.

Another theory says that bird feathers aren’t naturally waterproof. But birds can make them water resistant by applying waxes from their preen glands.

You may have watched a pet parrot grooming its own feathers – the bird will alternately rub its head against the base of its tail, and against its other feathers. It is depositing waxy, water-resistant oils found in the preen gland (at the tail base) onto the other feathers.Birds also have a dusty powder in their feathers. This powder comes from special feathers called “powderdowns”, which are constantly disintegrating into waterproof powder. This powder adds to the water-resistant quality of feathers.

It is essential for birds like ducks to constantly preen their feathers to keep them in good shape, and to keep distributing these waterproof oils and powders.Seabirds that dive underwater have particularly dense feathers, which also helps water from penetrating through the feathers to the bird’s body.

Hope that helps

 

[Ameena Eesa]

View attachment 40846

...

 

[Ameena Eesa]

Lead and iron do


Look at these animations
http://learnthings.co.za/content/se...e10/chemicalr/redoxreac/colourcha/default.htm

Actually I'd already seen these animations, i couldn't get the reactions though

 

[Ameena Eesa]

Aswk. In electrolysis, the metal ions travel from the solution to the cathode or from the anode to the cathode? What's the purpose of keeping the metal ions in both places? Plz help.

 

[Ameena Eesa]

How can electrical energy be produced from simple cells?

 

[My Name]

dogs have more number canines as compared to humans

YES BECUZ THEY ARE carnivores!
THER NEED TO TEAR FLESH!

 

[Awesome12]

Thank you, bro. And could you tell me one more thing, that, what are the products of heating a metal
1) Nitrate
2) Hydroxide

Does it differ from metal to metal?
Thank you.

Depends on the metal you have
For example (lets consider the reactivity series) the first two are stable to heat, however their nitrates decompose to metal nitrite and O2
The next elements until copper (including Cu);
Their hydroxides decompose to metal oxide and water
Their nitrates decompose to metal oxide, nitrogen dioxide, and O2



The products of the decomposition of elements below Cu;
The hydroxides a carbonates do not exist
Their nitrates decompose to metal, O2 and NO2

 

[Ameena Eesa]

Depends on the metal you have
For example (lets consider the reactivity series) the first two are stable to heat, however their nitrates decompose to metal nitrite and O2
The next elements until copper (including Cu);
Who'sTheir hydroxides decompose to metal oxide and water
Who's --Their nitrates decompose to metal oxide, nitrogen dioxide, and O2



The products of the decomposition of elements below Cu;
The hydroxides a carbonates do not exist
Their nitrates decompose to metal, O2 and NO2

What about SodiumOH or CuOH. Application of heat gives us what?

--and please see in your quote-- who's decomposition are you talking of?--

 

[Ameena Eesa]

describe the displacement of ammonia from its salts Plz

 

[shoaib672002]

View attachment 40803
Awesome12
shoaib672002
shazmina

Yes

T2 is less than T1.

 

[shoaib672002]

shoaib672002
shazmina
Awesome12
View attachment 40809

Yes (if your answer lies within 10%) otherwise No

Also for the justification U have to compare the two resistances and Hopefully the answer that is expected is that the first was close enough to being half the second

Hope U got it
-shoaib672002

 

[Incartyyy]

Aswk. In electrolysis, the metal ions travel from the solution to the cathode or from the anode to the cathode? What's the purpose of keeping the metal ions in both places? Plz help.

electrons always move from anode to cathode ( when using inert electrodes) and in this condition, the ions come in the solution ..suppose u take inert electrodes and do electrolysis for NaCl..Cl (-) would lose the electrons and sodium on the other hand which would be attracted to cathode would gain the electron from Cl..if u use non inert electrodes so the purpose of keeping the metal electrodes and electrolyte of same metal is to nt letting the electrolyte get used up.. there's suppose to take place the replacement of ions in the electrolyte so that it doesnt get used up..

 

[Kareem Ahmad]

Can you post some tips for IGCSE biology paper 6 & biology paper 3 ecology ?

 

[Incartyyy]

View attachment 40846

the small lines at the u can see on the outer circle are the root hair cells
cortex is the rest of the part except the middle area

 

[shoaib672002]

the small lines at the u can see on the outer circle are the root hair cells
cortex is the rest of the part except the middle area

the small lines at the u can see on the outer circle are the root hair cells
cortex is the rest of the part except the middle area

Thanks

 

[Incartyyy]

describe the displacement of ammonia from its salts Plz

the salts of ammonia for example ammonium chloride are bit acidic so then farmers put CaO or Ca(OH)2 to neutralize it.. if this basic oxide is put in excess then Ammonia gets displaced..so it goes like that
2NH4Cl + Ca(OH)2 -----> 2NH3 + 2H2O + CaCl2

 

[Ameena Eesa]

electrons always move from anode to cathode ( when using inert electrodes) and in this condition, the ions come in the solution ..suppose u take inert electrodes and do electrolysis for NaCl..Cl (-) would lose the electrons and sodium on the other hand which would be attracted to cathode would gain the electron from Cl..if u use non inert electrodes so the purpose of keeping the metal electrodes and electrolyte of same metal is to nt letting the electrolyte get used up.. there's suppose to take place the replacement of ions in the electrolyte so that it doesnt get used up..

Naww... like if you want to electroplate a spoon with copper. Copper will be the anode and the electrolyte will be for instance, copper sulphate. So copper will go to the cathode (where the spoon is), from the cathode or from the copper in the electrolyte? What's the purpose of keeping a COPPER electrolyte?... can't we just simply use any salt? , because anyway Cu is, i think, gonna get deposited on the spoon from the anode itself...pl explain

 

[Mai(M4!)]

what do i need to know and study specifically for alternative to practical bio paper??

 

[Incartyyy]

see basically the ions r taken frm the solution..CU ions would be taken frm the solution of its own!! so the ions that would be release the anode would replace the ions lost frm the solution

 

[Incartyyy]

what do i need to know and study specifically for alternative to practical bio paper??

go through all the experiments frm the book and practise plenty of past papers