Biology; Chemistry; Physics: Post your doubts here!

[Anon]

BTW Salman,
What should I do, in Chemistry now?

Read book, or continue with pastpapers? or something else?

Ur concepts aren't clear! see when teacher explains the topic it goes through my head because i hate chemistry! :evil:
anyways I suggest u read the book and solve past papers because by solving topical MCQ clear's the concepts!

Which one first?
MCQs or Book?

 

[SalmanPakRocks]

Book definetly
then MCQ then Theory!

 

[Anon]

OK, so am now going for the book..

I might just attempt this again later in the night.
Again, thanks for your help. You dont realise how much it helped me !
BYe for now. :Rose:

 

[SalmanPakRocks]

no problem! Glad i could help!

 

[memyself15]

OK, so am now going for the book..

I might just attempt this again later in the night.
Again, thanks for your help. You dont realise how much it helped me !
BYe for now. :Rose:

if you are preparing for exams then try doing this. read a chapter from book and try to clear the concepts. if you don't understand a point, try reading another book,or discuss it with a friend or teacher. then do MCQs for that chapter. try to suggest why other option are not correct. then go for theory. also read examination reports.

 

[Anon]

memyself15: earliar I had read your post, and did the very same.

Just want to confirm:

-All nitrates are soluble except for barium nitrate.
-All sulphates are soluble except calcium, barium(they have low solubility)
-All oxides are insoluble except the Alkali metals and calcium.
-All carbonates are insoluble except for Alkali metals.

Is this is right?

 

[SalmanPakRocks]

@memyself15: earliar I had read your post, and did the very same.

Just want to confirm:

-All nitrates are soluble except for barium nitrate.
-All sulphates are soluble except calcium, barium(they have low solubility)
-All oxides are insoluble except the Alkali metals and calcium.
-All carbonates are insoluble except for Alkali metals.

Is this is right?

hope this helps

 

[Anon]

This is indeed helpful.
I would like to know where did you get it from...

BTW, I usually crop up the image in Ms Paint after taking a screenshot, so to reduce upload time

EDIT: ignore the "BTW" thing. I just noticed it is a attachment

 

[Anon]

nvm,
I found it !

 

[SalmanPakRocks]

This is indeed helpful.
I would like to know where did you get it from...

BTW, I usually crop up the image in Ms Paint after taking a screenshot, so to reduce upload time

EDIT: ignore the "BTW" thing. I just noticed it is a attachment

Actually I was in a hurry so couldn't crop it! its the Ray notes for chemistry! Glad u found it!

 

[Anon]

The definition of
Endothermic and Exothermic is wrong in it. It is reversed.. just correcting

 

[SalmanPakRocks]

Oh well i haven't seen it yet.

 

[Silent Hunter]

yes... correct.... they have described exo and endo thermic in reverse ...

 

[Anon]

Does aqueous Bromine decolourises only when added to Alkenes, or does it decolourises whenever there is a double bond in the organic compund (e.g. carboxylic acid)?

 

[Silent Hunter]

i dont think so...........it just decolorises in alkenes.... thts what i studied in Olevels

 

[abcde]

Does aqueous Bromine decolourises only when added to Alkenes, or does it decolourises whenever there is a double bond in the organic compund (e.g. carboxylic acid)?

Bromine water decolourises compounds where a double bond exists between 2 carbon atoms. Not carboxylic acids as they possess a carbon-oxygen double bond, which is not affected by the addition of aqueous bromine.

 

[Silent Hunter]

correct

 

[SalmanPakRocks]

I have a problem with this MCQ
1)Which Industrial Process uses Iron as a Catalyst?
A) Making Ammonia from Nitrogen and Hydrogen.
B) Making ethanol from ethene and steam.
C) Making Steel
D) Making Sulphur trioxide from making Sulphur dioxide and oxygen.

I think the answer is D. but in the Redspot past paper book its A.

 

[sweetiepie]

i know why bt cant able to explain it properly to u

 

[Anon]

It is A.

Iron powder is used as catalyst in haber process.