AS Chemistry Doubts

[perkypearl]

oct/nov 2006 question1 http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf

 

[Student12]

oct/nov 2006 question1 http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w06_qp_1.pdf

50 cm^3 of H20 contains CaSo4
For 1 Ca+ --> 2H+ iona are exchanged.
Mole of KOH needed to neutralise the acid is c=n/v = (1.0 x 10^-2) x (25/1000) = 2.5 x 10^-4
Ca : H
1 : 2
Ca+ = (2.5 x 10^-4 / 2 ) = 1.25 x 10 ^-4 mol
Con. of CaSO4 = c = n/v = ( 1.25 x 10^-4) / (50/ 1000) = 2.5 x 10^-3

 

[perkypearl]

m/j 2006 q16 http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf

 

[smartangel]

m/j 2006 q16 http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s06_qp_1.pdf

you have to write the equation first. Ca(no3)2 -----> CaO + 2No2 + 0.5 O2
now calculate the moles of Ca(no3)2 by 4.10/164.1
you knw frm the equation the ratio of cao to ca(no3)2 is 1 :! hence moles will be same. therefore. just use mass= mr x moles and you:ll get the ans as C

 

[smartangel]

Please help me with Q40..PLEASE. i really dont get it. http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w09_qp_12.pdf

 

[smartangel]

http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q26!!

 

[Apple Ipad64]

h

Do as many past papers as you can.
I've done every P1 paper from summer 2002 to winter 2011, including variants
Plus I've done them three times, over and over again.

how come?:S

 

[1357913579]

please some one help as soon as possible
oct/nov 2010 second variant numer-7,18,31,34,36. soory for so much question but what can i do the paper semmed hard for me got these mistakes and unfortunately coudnt resolve any of my mistakes

thanks for helping all xpc members
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf

is there someone who can help please

 

[gestetner]

Help required in Q 1, 2, 40 of May/June 2005 P1
http://www.xtremepapers.com/papers/...d AS Level/Chemistry (9701)/9701_s05_qp_1.pdf

 

[1357913579]

Takes a few days only, if you know your subject.
P.S guys I am not solving chem questions until 15 May, studying bio and math...

bro we have p-1 exam on 9th may and your saying youll help after 15 what's the use then, please help

 

[raamish]

http://www.xtremepapers.com/papers/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf

Qs 10 plzz help

 

[raamish]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
Q26!!

It is said in the question that the alcohol is unbranched so it will not have any isoemrs. hence its formula will be : (oh)ch2ch2ch2ch2(oh) so OH groups are attached to 1st and 4th carbon atoms ))

Now please help me in my qs as well.

 

[Paparazzi478]

In May June 2011 Q.20 it says what statement about acrylic acid is not correct?
A.Both bond angles are 120.
B.It decolourises Bromine.
C.It gives an orange ppt with 2-4 dinitrophenyl hydrazine.
D.Ir reacts with an alcohol to form an ester.
According to the mark scheme,the answer is C.Why is that?Acrylic acid consists of a carbonyl carbon so it should give an orange ppt with 2-4 dinitrophenyl hydrazine.shouldn't it?

look again carefully it is a carboxylic acid not aldehyde or ketone.

 

[Inert.Phantom]

2.920 g of a Group II metal, X, reacts with an excess of chlorine to form 5.287 g of a compound
with formula XCl2.
What is metal X?
A barium
B calcium
C magnesium
D strontium

 

[Inert.Phantom]

2.920 g of a Group II metal, X, reacts with an excess of chlorine to form 5.287 g of a compound
with formula XCl2.
What is metal X?
A barium
B calcium
C magnesium
D strontium

 

[Adnaan Kapadia]

hows the answer A?[/quote]

X2H6 has a one X-X bond and 6 X-H bonds.The eqn given above is thatenthalpy change of formation meaning all these bonds were formed.......The energy released during bond formation is equal in magnitude but with a negative sign to the bond energy(coz its exothermic).........So we have 2775 = 6 * 395 +x .................Answer is 405

How do u know that there is one x-x bond and 6 x-h bond?

 

[perkypearl]

ohh okayy 28 29 30 ? got answers?

yah i got the answers .. for
Q.28 as -CH2CO2CH3 is a ion and in aldehyde the carbon will become partially positive so the ion will attack the carbon and make bond with it .. the O double bond of aldehyde will breakdown and H will be attached to oxygen
Q.29 the compound should have Br2 attched which will be replaced by CN and thn CN will i think oxidise to carboxylic acid
Q.30 the bond between C and o will break and H will be attchhed to O and alcohol will be produced and to to other fragment which is O with double bond and one hydrogen will be attacked by OH and will become acid

I HOPE MY EXPLANATION IS RIGHT !!

 

[1357913579]

please can you explain a bit more because iam stii not able to understand it

please explain

 

[sidbloom]

A small Dua before attempting the Paper for all O and A levelz

1. Read 3 time's durood -e -pak
2. Read 4 time's surah Fatihah
3. Read 3 time's Surah Iklas
4. And Pray To allah

Ya! Allah tamam Studnts ko ache marks se pass krde or jin ke paper ho rhy jen or hone wale hai un ke paper ache se ho jaye or jus ne mujhe ye dua send ki hai us ko bhi kamyabi ata kar and ham sab ko apni Panah me lay leh (ameen).....

 

[samwickz]

The first time: no more than 3o marks
The second time: no less than 30 marks
The third time I did them: no less than 36 marks
There are a number of reasons for this:
1)CIE repeats questions:4 extra marks
2)I became confident:2-5 extra marks
3)I became familiar with the style of the questions: 4-6 extra marks
P.S: dude like my post already
Just takes the push of a button!

ur funny lol