Chemistry MCQ thread...

[Abhi Mevawala]

in 1 the produt will be CH3CH(ONA)CO2NA
thts y 1 is incorrect

 

[geminisign]

in 1 the produt will be CH3CH(ONA)CO2NA
thts y 1 is incorrect

Oh I missed that. Cheers for the help really appreciate it!

 

[*MK*skydiver :D]

X has only Al and C in it. So all C in CO2 formed comes from the compound X.
n(CO2)=72/24000 mol, so that means m(CO2)=0.132g. From this fraction of C is 12/44 x 0.132g=m(C)=0.036g which is found in compound X.
So then m(Al)=0.132-0.036=0.108
From that you can work ratio of Al:C using method to find empirical formula. Ratio of Al:C turns out to be 4:3, so then answer is C which is the only multiple.

Very helpful , thank you

 

[*MK*skydiver :D]

you guys , i have some questions

#33 in June 12 Variant 2 : why isn't the concentration of SO4 high?
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_12.pdf


In Al2Cl6 , how many non-bonded electron pairs are there ?



#35 I found , online, that the products of this reaction are N2 ,BaO, and MgO , but how am i expected to deduce this in an exam ?
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_w11_qp_12.pdf

 

[kingo44]

How many hydrogen atoms in a molecule of glycerol, HOCH2CH(OH)CH2OH, may be substituted
by deuterium on dissolving it in an excess of D2O?
A 2 B 3 C 5 D 8

 

[Abhi Mevawala]

How many hydrogen atoms in a molecule of glycerol, HOCH2CH(OH)CH2OH, may be substituted
by deuterium on dissolving it in an excess of D2O?
A 2 B 3 C 5 D 8

3all the oh bond will be replaced by OD

 

[kingo44]

only like this impossible it is harder

 

[Abhi Mevawala]

no u will study in A2 level tht D is replaced by H when its OH

 

[kingo44]

where can u do a2 level

 

[Abhi Mevawala]

wat
do u mean?

 

[isa2hard]

14 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 pls i dont get how to do this one

 

[isa2hard]

15 The reaction between KI and concentrated H2SO4 is a redox reaction.

5H2SO4 + 8KI → 4K2SO4 + 4I2 + H2S + 4H2O

What is the change in oxidation state of the element that is reduced?
A 1 B 4 C 6 D 8
help pls

 

[Abhi Mevawala]

14 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 pls i dont get how to do this one

Ans is D
X(NO3)2+O2=XO+2NO2(g)+1.5O2(g)
nw 3-1.53=1.47 produced is XO as both the other productzz are gases
nw moles of X(NO3)2=moles of XO
so 3/(X+124)=1.47/(x+16)
from here u gt X as 87.7
so it strontium

 

[Abhi Mevawala]

15 The reaction between KI and concentrated H2SO4 is a redox reaction.

5H2SO4 + 8KI → 4K2SO4 + 4I2 + H2S + 4H2O

What is the change in oxidation state of the element that is reduced?
A 1 B 4 C 6 D 8
help pls

H2SO4 is an good oxidising agent so it will be reduced to H2S
in H2SO4 oxidtion no. of sulphur is +6
in H2S its -2
So the change is 8
tht is option D

 

[aysha aamer]

Titanium(IV) oxide, TiO2, is brilliantly white and much of the oxide produced is used in the
manufacture of paint.

What is the maximum amount of TiO2 obtainable from 19.0 tonnes of the ore ilmenite, FeTiO3?
A 10.0 tonnes B 12.7 tonnes C 14.0 tonnes D 17.7 tonnes
The answer is A. How do I solve this?

 

[hacker]

Mr of FeTiO3 = 55.8+47.9+16*3 = 151.7
Mr of TiO2 = 47.9+ 16*2 = 79.9
So amount of TIO2 in 19 tonnes of FeTiO3 = 79.9/151.7 x 19 = 10.0 tonnes

Titanium(IV) oxide, TiO2, is brilliantly white and much of the oxide produced is used in the
manufacture of paint.

What is the maximum amount of TiO2 obtainable from 19.0 tonnes of the ore ilmenite, FeTiO3?
A 10.0 tonnes B 12.7 tonnes C 14.0 tonnes D 17.7 tonnes
The answer is A. How do I solve this?

 

[aysha aamer]

Mr of FeTiO3 = 55.8+47.9+16*3 = 151.7
Mr of TiO2 = 47.9+ 16*2 = 79.9
So amount of TIO2 in 19 tonnes of FeTiO3 = 79.9/151.7 x 19 = 10.0 tonnes

Thank you

 

[SomeStudent]

The answer is C. I only got two different types.. whats the third one?

 

[aysha aamer]

The answer is C. I only got two different types.. whats the third one?

Based on our alkane's structure, we get one distinct alkyl radical if one of the hydrogens on carbon 1 or either of the methyls is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → ·CH2(CH3)2−C−CH2−CH3 + HCl
We get a second distinct alkyl radical if one of the hydrogens on carbon 3 is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → (CH3)3−C−·CH−CH3 + HCl
And we get a third distinct alkyl radical if one of the hydrogens on carbon 4 is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → (CH3)3−C−CH2−CH2· + HCl

 

[SomeStudent]

Based on our alkane's structure, we get one distinct alkyl radical if one of the hydrogens on carbon 1 or either of the methyls is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → ·CH2(CH3)2−C−CH2−CH3 + HCl
We get a second distinct alkyl radical if one of the hydrogens on carbon 3 is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → (CH3)3−C−·CH−CH3 + HCl
And we get a third distinct alkyl radical if one of the hydrogens on carbon 4 is pulled off:
(CH3)3−C−CH2−CH3 + Cl· → (CH3)3−C−CH2−CH2· + HCl

Got it! Thanks!