Biology; Chemistry; Physics: Post your doubts here!

[AhsanAfzal]

From which chapter is that?

dehydration of alcohol is to make alkenes from from alcohol in presence of h2So4 and 180 Celsius temp and water is also a product

 

[robinhoodmustafa]

in the pipette question the mark which shows 25 cm3 should be on top part. right?(in imran merchant paper)

I think the error is that the Point of the Pipette is not Pointy from the end

 

[robinhoodmustafa]

I was thinking of the exact same thing. Iron reacts with water (and air) to form rust (brown solid).
The thing is they're only asking for the reaction with water. Iron doesn't react with water, it reacts with steam, so that's that.

But Steam is water

 

[AhsanAfzal]

I think the error is that the Point of the Pipette is not Pointy from the end

but my answer should be right too...

 

[Saad Mughal]

But Steam is water

Steam is well, a gas. It is water vapour, but when they ask, the reaction of sodium and iron with water, I think they mean water, not steam.

 

[Saad Mughal]

but my answer should be right too...

You're answer is correct, it's in the markscheme, 2003 june.

 

[Snowysangel]

I think the error is that the Point of the Pipette is not Pointy from the end

No no notice how the liquid level is marked at the bottom when it should be at the top? That's the error!

 

[ijlalm]

can i get the link of imran merchant's guess paper??

 

[sourov97]

can i get the link of imran merchant's guess paper??

https://www.xtremepapers.com/commun...stry-guess-paper-by-imran-merchant-docx.25046

 

[usama321]

I think the error is that the Point of the Pipette is not Pointy from the end

 

[AhsanAfzal]

Why is lid placed on the crucible when making magnesium oxide?

 

[robinhoodmustafa]

No no notice how the liquid level is marked at the bottom when it should be at the top? That's the error!

But that depends on the person Pumping the liquid. Have u ever notice when we are drinking something with a straw so we can Control the water level in it.. Hope u undertstand.

I asked my Dad and He said that it shud be pointy.

 

[robinhoodmustafa]

Why is lid placed on the crucible when making magnesium oxide?

So that no pressure builds up inside and prevent the apparatus from exploding.

Just remember the Pressure cooker.. Pressue builds up.If there is no Exit for the pressure(Heat) than It can explode

 

[robinhoodmustafa]

Steam is well, a gas. It is water vapour, but when they ask, the reaction of sodium and iron with water, I think they mean water, not steam.

Ok

 

[robinhoodmustafa]

but my answer should be right too...

ok Your right..

 

[ijlalm]

the guess paper is quite easy!!

 

[AhsanAfzal]

with moist blue litmus chlorine first makes it red then bleaches it, right?

 

[Ishrar Afrida]

Q.1 (C,D,E) Can anyone please explain me the calculations clearly? Have a exam tomorrow.

 

[ijlalm]

with moist blue litmus chlorine first makes it red then bleaches it, right?

yeah

 

[robinhoodmustafa]

with moist blue litmus chlorine first makes it red then bleaches it, right?

why go in such dept.

Litmus paper is not just Blue and red. there is also a White color one so U just write Turns damp litmus paper red and than bleaches it