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P1 MCQ's preparation thread for chemistry ONLY!!!!

Obsidian Fl1ght

Obsidian Fl1ght

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Also:
I need the explanation:

13 How does concentrated sulfuric acid behave when it reacts with sodium chloride?
A as an acid only
B as an acid and oxidising agent
C as an oxidising agent only
D as a reducing agent only

Ans. is A.


And:
q13 - in attachment.
ANs. A again
Thanks in advance.
 

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  • 9701_s10_qp_11.pdf
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queen of the legend

queen of the legend

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S

samiaaaaaaaaaaaaahhh

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can someone give me solutions of nov2012 variant 12 q1 ,q4, q10, q23, q29, q33, q35, q39 and q40!! please tell me the solution soon! i am really worried
 
Raweeha

Raweeha

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samiaaaaaaaaaaaaahhh said:
can someone give me solutions of nov2012 variant 12 q1 ,q4, q10, q23, q29, q33, q35, q39 and q40!! please tell me the solution soon! i am really worried
Click to expand...

Have you tried reading the examiner's report? Common errors are often explained in there.
 
Raweeha

Raweeha

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queen of the legend said:
m /j 2012 pls variant 11

question 33, 37 explain
Click to expand...

For 33, The answer is D, as nitrogen can have an ox. state of +5 in N2O5, therefore 2 is incorrect. 3 is incorrect too, as this would mean that nitrogen would not form any compounds, which is untrue. Which leaves 1 - this is correct as nitrogen's electronic config. is 1s2 2s2 2p3 and it has space to accommodate more electrons in its empty third sub-shell.

For 37, 3 is incorrect as a pi bond does not consist of delocalized electrons, it is just an area of high electron density. Remember that ethene, for example, cannot conduct electricity! That leaves 1 and 2, which are correct, so the answer is B.

I hope that helped :)
 
itallion stallion

itallion stallion

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Raweeha said:
For 33, The answer is D, as nitrogen can have an ox. state of +5 in N2O5, therefore 2 is incorrect. 3 is incorrect too, as this would mean that nitrogen would not form any compounds, which is untrue. Which leaves 1 - this is correct as nitrogen's electronic config. is 1s2 2s2 2p3 and it has space to accommodate more electrons in its empty third sub-shell.

For 37, 3 is incorrect as a pi bond does not consist of delocalized electrons, it is just an area of high electron density. Remember that ethene, for example, cannot conduct electricity! That leaves 1 and 2, which are correct, so the answer is B.

I hope that helped :)
Click to expand...


can u plz help me with this http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_11.pdf q9.thanks alot!
 
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Xeshan16

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Mairaxo said:
yeah sorry it does react and an O is attached to both ends of the double bond! my bad :p
Click to expand...

Sorry for Bro :p #examtime
What do you mean that an O is attached to both end of alkene? CAn you tell me the product of this reation?
 
M

mehranshaikh

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Obsidian Fl1ght said:
A question:
(I'll just summarize it:)

3 equations:

Cl2 + 2H20 + SO2 ---> 2HCl + H2SO4
Cl2 + H2S ----> 2HCl
SO2 + 2H2S ---> 2H2O + 3S

What's the correct order of strength of the 3 reacting gases as REDUCING agents?

Strongest Weakest
A Cl2 H2S SO2
B Chlorine SO2 H2S
C Hydrogen Sulfide SO2 Cl2
D Sulfur dioxide H2S Cl2


The answer is C.
Anyone who can explain why??
Thank u in advance!
Click to expand...

In the first reaction SO2 reduces Cl2 to HCL. So it is stronger reducing agent than Cl2. SO2 > Cl2
In the second reaction H2S reduces Cl2 to HCl. So it is stronger than Cl2. H2S > Cl2
In third reaction H2S reduces SO2 to S. So it's stronger than SO2. H2S> SO2
H2S> SO2> Cl2
 
M

mehranshaikh

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Obsidian Fl1ght said:
s10_qp11:
Q22:

What will react differently with the two isomeric alcohols, (CH3)
3
CCH2
OH and
(CH3)
2
CHCH2
CH2
OH?
A acidified aqueous potassium manganate(VII)
B concentrated sulfuric acid
C phosphorus pentachloride
D sodium

Answer's B. WHY?
Click to expand...

First one is a tertiary alcohol. If you draw out the structure you would see that it cannot be dehydrated as the carbon adjacent to the carbon which is attached to OH group has no H attached. The second one can be dehydrated using Sulpuric Acid.
 
M

mehranshaikh

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Obsidian Fl1ght said:
Also:
I need the explanation:

13 How does concentrated sulfuric acid behave when it reacts with sodium chloride?
A as an acid only
B as an acid and oxidising agent
C as an oxidising agent only
D as a reducing agent only

Ans. is A.


And:
q13 - in attachment.
ANs. A again
Thanks in advance.
Click to expand...

Sulphuric Acid reacts as an acid only as it does not oxidise the HCl formed. In reactions with NaBr and NaI the products are further oxidised.
 
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