Chemistry and Physics AS paper 12 MCQS

[IGCSEstudent2012]

Can anybody explain this to me? It's q1 in May June 2004..

1 Which of these samples of gas contains the same number of atoms as 1g of hydrogen (Mr: H2 = 2)?
A) 22g of carbon dioxide (Mr: CO2, 44)
B) 8g of methane (Mr: CH4, 16)
C) 20g of neon (Mr: Ne, 20)
D) 8g of ozone (Mr: O3, 48)

Aren't A and B the same answer?

yes they are the same...is the ans C??

 

[snowbrood]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
ques 6 prettyplease!
snowbrood

number of moles in ice= number of moles in steam
density is 1 volume is 1 mass would be 1 g then
find the number of moles 1/18=0.056 of steam
PV=nRT
101k*V=0.056*8.13*596
u get V as 2.67*10^-3 it is m^-3 (dont use number of moles as 0.056 put the value 1/18)
1000cm^3=1dm^3
100cm=1m
cube both sides u get
1,000,000cm^3=1m^3
1dm^3 (1/1000)m^3
x 2.67*10^-3
solve this by direct proportion

 

[HubbaBubba]

yes they are the same...is the ans C??

Why is it C? The answer is supposed to be C but it doesn't make sense to me. 1g/2 = 0.5moles of H2. 05 moles * 6.02 * 10^23 = 3.01 * 10^23

 

[IGCSEstudent2012]

number of moles in ice= number of moles in steam
density is 1 volume is 1 mass would be 1 g then
find the number of moles 1/18=0.056 of steam
PV=nRT
101k*V=0.056*8.13*596
u get V as 2.67*10^-3 it is m^-3 (dont use number of moles as 0.056 put the value 1/18)
1000cm^3=1dm^3
100cm=1m
cube both sides u get
1,000,000cm^3=1m^3
1dm^3 (1/1000)m^3
x 2.67*10^-3
solve this by direct proportion

thanxx a loott!

 

[IGCSEstudent2012]

Why is it C? The answer is supposed to be C but it doesn't make sense to me. 1g/2 = 0.5moles of H2. 05 moles * 6.02 * 10^23 = 3.01 * 10^23

no there is no calculation...
H is 1g so H2 = 2g ..this means that 1 atom of H is 1g
so..Mr of Ne is 20 which means 20g of Ne has each atom of 1g like H
got it?

 

[Aries_95]

Why is it C? The answer is supposed to be C but it doesn't make sense to me. 1g/2 = 0.5moles of H2. 05 moles * 6.02 * 10^23 = 3.01 * 10^23

The question says the mass of HYDROGEN ATOMS, we take the mr to be 1 and the mass is 1g which give us 1 mole.
Since Ne has mr of 20, and the mass is 20, the moles will be equal to 1. the no of atoms are thus same to that of 1 g of HYDROGEN ATOMS.
Hope you understand

 

[HubbaBubba]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf

How do we do question 10? I got the answer as 2 atm, but marking scheme says it's C (4/3 atm)

 

[cute97]

ANYONE PLS
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Q11 how to do such ques, Q21, Q39 what are the H2SO4 reactions ??
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Q9, Q19, Q28
thanks in advance

 

[Aries_95]

ANYONE PLS
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Q11 how to do such ques, Q21, Q39 what are the H2SO4 reactions ??
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Q9, Q19, Q28
thanks in advance

w_07:
Q19:
yaar optical isomers are those which form mirror images. Out of these options, I,II and III only form mirror images (Try making them...hopefully you'll understand).
Q.28:
when reduced, aldehydes produce a primary alcohol. also addition of H2 along with nickle catalyst causes the addition of H2 to the double bonds and not NaBH4...hence the option is A.

w_06:
Q.39:
H2SO4 acts as a dehydrating agent/ reducing agent.
1 copound is an aldehyde which can be reduced to produce primary alcohol which decolorises KMNO4.
2 compound decolorises KMNO4 since it is oxidised to producea a ketone (it is a secondary alcohol)
3 compound is a carboxylic acid which produces primary alcohol which can decolorize KMNO4.
hence A is the answer.
Q.21:
Put the values of n from 1- 4
ie C2H(6-1)Cl--->C2H5Cl
C2H(6-2)Cl2---->C2H4Cl2
C2H(6-3)Cl3---->C2H3Cl3
C2H(6-4)Cl4---->C2H2Cl2
Draw the isomers of each compound but make sure you do not draw Cl2 twice on the same position ex at the start and the end of the compound..that will be counted as one isomer not two different ones.

 

[cute97]

GUYZZZ CHECK THIS REPEATED QUESTION THE MARK SCHEME GAVE TWO DIFFRENT ANSWERS !!! HELP
Q12http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf
and this is the mark scheme for JUNE 06
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_ms_1.pdf
Q11http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf
and this is the mark scheme for NOVEMBER 11
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_ms_11.pdf
what is the correct answer ????​

 

[Aries_95]

GUYZZZ CHECK THIS REPEATED QUESTION THE MARK SCHEME GAVE TWO DIFFRENT ANSWERS !!! HELP​

Q12http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_qp_1.pdf ​

and this is the mark scheme for JUNE 06​

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s06_ms_1.pdf​

Q11http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_11.pdf​

and this is the mark scheme for NOVEMBER 11​

http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_ms_11.pdf​

what is the correct answer ????​

The answers are correct.
Look again at the options, they are shuffled. the option C in s_O6 is option A in w_11 hence the answers are C and A respectively.

 

[cute97]

w_07:
Q19:
yaar optical isomers are those which form mirror images. Out of these options, I,II and III only form mirror images (Try making them...hopefully you'll understand).
Q.28:
when reduced, aldehydes produce a primary alcohol. also addition of H2 along with nickle catalyst causes the addition of H2 to the double bonds and not NaBH4...hence the option is A.

w_06:
Q.39:
H2SO4 acts as a dehydrating agent/ reducing agent.
1 copound is an aldehyde which can be reduced to produce primary alcohol which decolorises KMNO4.
2 compound decolorises KMNO4 since it is oxidised to producea a ketone (it is a secondary alcohol)
3 compound is a carboxylic acid which produces primary alcohol which can decolorize KMNO4.
hence A is the answer.
Q.21:
Put the values of n from 1- 4
ie C2H(6-1)Cl--->C2H5Cl
C2H(6-2)Cl2---->C2H4Cl2
C2H(6-3)Cl3---->C2H3Cl3
C2H(6-4)Cl4---->C2H2Cl2
Draw the isomers of each compound but make sure you do not draw Cl2 twice on the same position ex at the start and the end of the compound..that will be counted as one isomer not two different ones.

Thank You . Sry but I dont have good chem and Iam so confused
W_07 Q19 isomer I and II are optical only !! and for Q28 NaBH4 wont add hydrogen to a double bond and it is used only in single bonds??
W_06 Q39 you mean the compund react with H2SO4 it forms an aldehyde which reacts with KMNO4 and decolorises it ??? and the same for the 2nd compound ?? but what abt the 3rd one ??? for Q21 the last one (4th) u mean C2H2Cl4??
thanks again

 

[cute97]

The answers are correct.
Look again at the options, they are shuffled. the option C in s_O6 is option A in w_11 hence the answers are C and A respectively.

hahahhahahhhaa its seems i must take a break now

 

[IGCSEstudent2012]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
please explain me these ques ..23,27,30 ..im so flunking chem:/
Aries_95 i know you'd help

 

[ahmed abdulla]

w_07:
Q19:
yaar optical isomers are those which form mirror images. Out of these options, I,II and III only form mirror images (Try making them...hopefully you'll understand).
Q.28:
when reduced, aldehydes produce a primary alcohol. also addition of H2 along with nickle catalyst causes the addition of H2 to the double bonds and not NaBH4...hence the option is A.

w_06:
Q.39:
H2SO4 acts as a dehydrating agent/ reducing agent.
1 copound is an aldehyde which can be reduced to produce primary alcohol which decolorises KMNO4.
2 compound decolorises KMNO4 since it is oxidised to producea a ketone (it is a secondary alcohol)
3 compound is a carboxylic acid which produces primary alcohol which can decolorize KMNO4.
hence A is the answer.
Q.21:
Put the values of n from 1- 4
ie C2H(6-1)Cl--->C2H5Cl
C2H(6-2)Cl2---->C2H4Cl2
C2H(6-3)Cl3---->C2H3Cl3
C2H(6-4)Cl4---->C2H2Cl2
Draw the isomers of each compound but make sure you do not draw Cl2 twice on the same position ex at the start and the end of the compound..that will be counted as one isomer not two different ones.

 

[samiaaaaaaaaaaaaahhh]

can someone solve the papers with solutions and post it here? please ! for chemistry and biology

 

[Aries_95]

Thank You . Sry but I dont have good chem and Iam so confused
W_07 Q19 isomer I and II are optical only !! and for Q28 NaBH4 wont add hydrogen to a double bond and it is used only in single bonds??
W_06 Q39 you mean the compund react with H2SO4 it forms an aldehyde which reacts with KMNO4 and decolorises it ??? and the same for the 2nd compound ?? but what abt the 3rd one ??? for Q21 the last one (4th) u mean C2H2Cl4??
thanks again

It's ok
No, draw the isomer for the third compound, it is optical as well.
NaBH4 is only a reducing agent thus won't add hydrogen to a double bond.
For Q.39: Yes since H2SO4 is also a reducing agent, aldehyde is produced. since it is oxidised, the color of KMNO4 changes from purple to colorless.
the last compound is a carboxylic acid. it is reduced to a primary alcohol. Primary alcohol decolorises KMNO4 since it can be oxidised.
And for Q.21 Yup.
Hope you understand

 

[Aries_95]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s08_qp_1.pdf
please explain me these ques ..23,27,30 ..im so flunking chem:/
Aries_95 i know you'd help

For Q.23:
D cannot be obtained when we heat pentane. the other options include CH4, C2H6 and C4H8 all of which can be obtained by heating pentane (Hope you have read about cracking before). Hence D will not be collected in the inverting tube.
For Q.30:
C6H12O is an aldehyde. when it is oxidised, it produces a carboxylic acid with the formula CH3CH2CH2CH2CH2CO2H.
When the carboxylic acid above is made to react with ethanol i.e CH3CH2OH, an ester is produced.
The formula of the ester is CH3CH2CH2CH2CH2CO2CH2CH3. OR CH3(CH2)4CO2CH2CH3. hence the answer is C.

 

[IGCSEstudent2012]

For Q.23:
D cannot be obtained when we heat pentane. the other options include CH4, C2H6 and C4H8 all of which can be obtained by heating pentane (Hope you have read about cracking before). Hence D will not be collected in the inverting tube.
For Q.30:
C6H12O is an aldehyde. when it is oxidised, it produces a carboxylic acid with the formula CH3CH2CH2CH2CH2CO2H.
When the carboxylic acid above is made to react with ethanol i.e CH3CH2OH, an ester is produced.
The formula of the ester is CH3CH2CH2CH2CH2CO2CH2CH3. OR CH3(CH2)4CO2CH2CH3. hence the answer is C.

thnx..ques 27 also?

 

[Aries_95]

thnx..ques 27 also?

Yaar I am not sure about 27. I mean i get confused between C and D.
Let me work it out and then i'll tell you too