Chemistry MCQ thread...

[aysha aamer]

How do i slove this?

 

[aaaamfa]

How do i slove this?

use the formula PV=nRT to find the Mr and then compare it with the mass of the elements given

 

[aaaamfa]

one mre

Acoording to me the ans is 1&2 as the volume of the container decreases the gas volume is no longer negligible to the volume of the container ans as the gas molecules start coming closer to each other emf builds up the gas no longer behaves ideally.when emf builds up the change in state of matter takes place so it liquifies

hope my explaination satisfies the answer

 

[hassankhan]

hi,can anyone help with this question?
The formula CH3 can represent an anion, a cation or a free radical. Species with the molecular
formula CH3 can act as an electrophile, a free radical or a nucleophile depending on the number
of outer shell electrons on the central carbon atom.
How many outer shell electrons must be present for CH3 to act in these different ways?

A 6 7 8
B 6 8 7
C 7 6 8
D 8 7 6

 

[Muslimah98]

hi,can anyone help with this question?
20 The formula CH3 can represent an anion, a cation or a free radical. Species with the molecular
formula CH3 can act as an electrophile, a free radical or a nucleophile depending on the number
of outer shell electrons on the central carbon atom.
How many outer shell electrons must be present for CH3 to act in these different ways?
CH3 as an CH3 as a CH3 as a
electrophile free radical nucleophile

A 6 7 8
B 6 8 7
C 7 6 8
D 8 7 6

I neeeeed the answer to this!! Does anyone know which year this is from?

 

[Mohamed Shalaby]

Hey everyone

 

[shaheerrn]

H3C
C

1. 28 Carvone gives the characteristic flavour to caraway and spearmint. O
   

CH3

Prolonged heating of carvone with hot concentrated acidified potassium manganate(VII) produces carbon dioxide and a compound X.

X contains nine carbon atoms and reacts with 2,4-dinitrophenylhydrazine reagent.
What is the maximum number of molecules of 2,4-dinitrophenylhydrazine that will react with one

molecule of X? A1B2C3D4

CH2 carvone

 

[kingo44]

i bewlive u meant nuclei

Q21, HELP!

Q 39: It's nucleophillic addition, since halogenoalkane is being hydrolyzed to alcohol, so 1 is right. X to Z does represent the activation energy, so 3 is right, which means that 2 has to be right aswell, so it's A.

(I'm guessing that since the C-Hal bond is breaking, so as it's length increases, the bond gets weaker and is eventually broken! :Search: )

ophilic substitution right

 

[$$AK$$]

Hi guys
How are u all?
i need help in http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w13_qp_12.pdf
Q8)
Q9)
Q13)
Q16)
Q17)
Q20)
THANK YOU GUYS
Even if u can help me only in few of them , I have NO PROBLEM

 

[Swetatmg]

[C₂H₅OH] | [CH₃COOH] | [CH₃COOC₂H₅] | [H₂O]
I 1.0 | 1.0 | 0 | 0
C -x | -x | +x | +x
E 1.0-x | 1.0-x | x |x

Kc = [CH₃COOC₂H₅] [H2O]/ [C₂H₅OH] * [CH₃COOH]
4=x^2 / (1-x)^2
2=x/(1-x)
X=2/3
So the answer is B

 

[Igcse stuff]

very helpful thread

 

[JAVERIA INAM DANISH]

from which year shall i start revising past paper?

 

[Zepudee]

Glycol, used in anti-freeze, has the formula HOCH2CH2OH. It can be oxidised to give a number of
products.

What is the molecular formula of an oxidation product of glycol that will not react with sodium?

A C2H2O2 B C2H2O3 C C2H2O4 D C2H4O2

 

[ashcull14]

 

[ashcull14]

 

[ashcull14]

 

[Ahmed Aqdam]

View attachment 44947

Formation of SO3 requires a catalyst as in Contact process.

View attachment 44949

A: N and H are not directly bonded.
B: Its not dimeric
C: Complete octet as three bonds with hydrogens and double bond with N.
D: Correct as four atoms bonded and no lone pair.

 

[ashcull14]

cn u ans q34 plz

 

[Ahmed Aqdam]

View attachment 44945

1 is endothermic so higher temperature will favour forward reaction. NF2 has more moles hence more volume so mercury level will rise.
2 is exothermic so higher temperature will favour backward reaction. Same number of moles so level falls as volume of R is more.
3 is nitrogen in both so level will fall again as volume of R is more.

 

[ashcull14]

1 is endothermic so higher temperature will favour forward reaction. NF2 has more moles hence more volume so mercury level will rise.
2 is exothermic so higher temperature will favour backward reaction. Same number of moles so level falls as volume of R is more.
3 is nitrogen in both so level will fall again as volume of R is more.

thnks a lot