Chemistry and Physics AS paper 12 MCQS

[kingos3111]

15 Ammonium sulfate in nitrogenous fertilisers in the soil can be slowly oxidised by air producing
sulfuric acid, nitric acid and water.
How many moles of oxygen gas are needed to oxidise completely one mole of ammonium
sulfate?
A 1
B 2
C 3
D 4

 

[h4rriet]

15 Ammonium sulfate in nitrogenous fertilisers in the soil can be slowly oxidised by air producing
sulfuric acid, nitric acid and water.
How many moles of oxygen gas are needed to oxidise completely one mole of ammonium
sulfate?
A 1
B 2
C 3
D 4

Construct a balanced equation.

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w10_qp_12.pdf
number-40 please

The profile shown is for an Sn1 mechanism reaction, i.e. a 2-step reaction, one in which only tertiary alcohols/halogenoalkanes/etc. will take part.

 

[h4rriet]

http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s03_qp_1.pdf
QUES 2 pls explain...i so bad in organic chem:/

1 C=C double bond with take 1 mole of H2. Count the number of C=C bonds initially present in the molecule, and then the number of C=C left after the reaction. Minus the second from the first to get the number of H2 moles.

 

[Franklin]

Exactly!

 

[hope4thebest]

w11_qp 12 question no 39
Help required! Thanks

 

[ahmed abdulla]

1 C=C double bond with take 1 mole of H2. Count the number of C=C bonds initially present in the molecule, and then the number of C=C left after the reaction. Minus the second from the first to get the number of H2 moles.

 

[h4rriet]

Attached files

26. You just draw all the alkenes you can get with C5H10. You can draw more than one C=C double bond in one isomer. You've also got to look out for cis-trans isomers.
29. C=C turns into COH-COH with cold, dilute KMnO4 and into C=O with hot, concentrated KMnO4.

 

[h4rriet]

w11_qp 12 question no 39
Help required! Thanks

An α-particle has a charge of 2+. It is a Helium nucleus. It does not make a gold nucleus radioactive.

 

[ahmed abdulla]

40 An organic compound, X, will react with an excess of calcium metal to produce a salt with the
empirical formula CaC4H6O4.
What could be the identity of X?
1 ethanoic acid
2 butanedioic acid
3 methylpropanedioic acid

answer is one only.. but i cant understand how 2 carbons changed to 4 ! with ethanoic acid ???????
any help "{

 

[cute97]

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

Thank you this was helpful

 

[carilove]

hey guys need help with http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_s05_qp_1.pdf question 1 and 2

thanks

 

[sufyanalizaib]

Use of the Data Booklet is relevant to this question.
When 3.00 g of an anhydrous nitrate of a Group II metal is decomposed, 1.53 g of gas is
produced.
What is the nitrate compound?
A beryllium nitrate
B calcium nitrate
C magnesium nitrate
D strontium nitrate hELP>>>>>>

 

[1597.2217]

15 Ammonium sulfate in nitrogenous fertilisers in the soil can be slowly oxidised by air producing
sulfuric acid, nitric acid and water.
How many moles of oxygen gas are needed to oxidise completely one mole of ammonium
sulfate?
A 1
B 2
C 3
D 4

(NH4)2SO4 + O2 ---> HsSO4 + HNO3 + H2O [Balance the equation]
(NH4)2SO4 + 4O2 ---> H2SO4 + 2HNO3 + 2H2O


Answer is (D).

 

[1597.2217]

40 An organic compound, X, will react with an excess of calcium metal to produce a salt with the
empirical formula CaC4H6O4.
What could be the identity of X?
1 ethanoic acid
2 butanedioic acid
3 methylpropanedioic acid

answer is one only.. but i cant understand how 2 carbons changed to 4 ! with ethanoic acid ???????
any help "{

Because 1 Mole of Calcium reacts with 2 Mole of acid.

 

[1597.2217]

hey guys need help with http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_s05_qp_1.pdf question 1 and 2

thanks

Q1:

The volume of Oxygen used is Initial-final = 70-20 = 50 Cm^3

This means 10cm^3 of X will react with 50cm^3 of O2 to give 30cm^3 of CO2 and H2O
With this we can make a equation giving the moles:

X + 5 O2 ---> 3 CO2 + y H2O [We can find y by 5x2 O2 - 3x2 O2 giving us 4 O which are in the H2O. So y=4)
X + 5 O2 ---> 3 CO2 + 4 H2O [Now calculate the number of C and H]

This gives us 3 C and 8 H. So answer is C3H8.


Q2:

From equation 1 we see that 2 moles of Sodium Azide gives us 3 moles of Nitrogen gas. So 1 mole gives 1.5 moles of Nitrogen gas.
From equation 2 we see that 10 moles of Sodium give 1 mole of Nitrogen. However, 2 Mole of Sodium Azide gives 2 Mole of Sodium. So 1 Mole of Sodium Azide will give 1 mole of Sodium. You divide the moles in second equation by 10 to get this:

Na + 0.2KNO3→ 0.1K2O + 0.5Na2O + 0.1N2

So your answer is 1.5 moles from first equation plus 0.1 moles from second equation to give 1.6 moles of Nitrogen gas, which is (B).

Hope you get it!

 

[1597.2217]

Use of the Data Booklet is relevant to this question.
When 3.00 g of an anhydrous nitrate of a Group II metal is decomposed, 1.53 g of gas is
produced.
What is the nitrate compound?
A beryllium nitrate
B calcium nitrate
C magnesium nitrate
D strontium nitrate hELP>>>>>>

2 X(NO3)2 → 2 XO + 4 NO2 + O2

First you need to calculate the moles of gas formed. You have 1.53g and the gas produced is NO2 and O2. So 1.53/2x(14+16+16) + 16 = 0.0142 moles. [1 Mole of salt gives 2 moles of NO2 and half mole of O2].

n=m/Mr
Mr = m/n
Mass of nitrate is 3g and moles is 0.0142. So 3/0.0142 = 211.267. The Mr of the Nitrate is 211.27. Now you can find the Mr of each salt given using periodic table.
The molecular formula must be X(NO3)2. We can find Mr of X as 211.27-(2x(14+3x16)). This gives 211.27-124 which is 87.3. From the periodic table, Strontium has Ar of 87.6 which is close to 87.3 therefore the salt must be (D).

(I hope I'm right, please confirm the answer from mark-scheme)

 

[mariamh]

Physics October NOvember 2003
q 16 and 28 plz help!!

 

[1597.2217]

Physics October NOvember 2003
q 16 and 28 plz help!!

I couldn't do Q16. Sorry.

As for Q28:
d= 0.08
L= 0.03

dSinx=nL
Sinx = nL/d
Sinx = 2x0.03/0.08
x= 46.6

However, we do not have to find the angle between incident ray and second order diffraction. We have to find between first order diffraction and second order diffraction. So, 46.6-22 gives 26.6 degree which is (B).

 

[cute97]

HELP PLS
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w06_qp_1.pdf
Q11 and Q14
http://papers.xtremepapers.com/CIE/...d AS Level/Chemistry (9701)/9701_w07_qp_1.pdf
Q9
Thanks is advance