Chemistry MCQ thread...

[abdullah181994]

PLEASE EXPLIAN UR WORKING ALSO

 

[abdullah181994]

2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to +
2
Cl were recorded?
A 2 B 3 C 4 D 5
EXPLAIN

 

[ideggkr]

Calcium?

 

[Mobeen]

2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to +
2
Cl were recorded?
A 2 B 3 C 4 D 5
EXPLAIN

answers B right ?

 

[Mssamgirl15]

Could someone please solve question number 7 of OCTOBER/NOVEMBER 2005 or click on the link below.

http://www.xtremepapers.me/CIE/Internat ... 5_qp_1.pdf

QUESTION 7

 

[ideggkr]

2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to +
2
Cl were recorded?
A 2 B 3 C 4 D 5
EXPLAIN

3 peaks observed.

I'll show workings if u confirm

 

[Mobeen]

yep 3 peaks . one of Cl35 one of Cl37 and one of their averaged molecule Cl35.5

 

[ideggkr]

Could someone please solve question number 7 of OCTOBER/NOVEMBER 2005 or click on the link below.

http://www.xtremepapers.me/CIE/Internat ... 5_qp_1.pdf

QUESTION 7

A?

 

[Mssamgirl15]

Could someone please solve question number 7 of OCTOBER/NOVEMBER 2005 or click on the link below.

http://www.xtremepapers.me/CIE/Internat ... 5_qp_1.pdf

QUESTION 7

A?

You're right, but how? Could you please explain?

 

[abdullah181994]

YES 3 PEAKS IS ANSWER

 

[abdullah181994]

2 A sample of chlorine containing isotopes of mass numbers 35 and 37 was analysed in a
mass-spectrometer.
How many peaks corresponding to +
2
Cl were recorded?
A 2 B 3 C 4 D 5
EXPLAIN

answers B right ?

YEH RIGHT

 

[Abdulrab]

the answer is B ??? right ?? for 14

 

[Mobeen]

YES 3 PEAKS IS ANSWER

i explained above .. one would be of the isotope of Cl35 , one would be of the isotope of Cl37 , and the third would be of the molecule Cl35.5

 

[abdullah181994]

Calcium?

YES BUT EXPLAIN PLEASE

 

[ideggkr]

Calcium?

YES BUT EXPLAIN PLEASE

1. Set up equation.

2X(NO3)2 --> 2XO + 4NO2 + O2 (I'm sure u did this step but just to make sure.)

And we know 2X(NO3)2 is 5.0g, and 3.29g is lost.
The lost mass represents masses of 4NO2 and O2 since 2XO is the only solid here.

2X(NO3)2 --> 2XO + 4NO2 + O2
(5.0g).......(1.71g)...(3.29g)

Let the mass of X = x, and set up a ratio

2(x+16) : 4(14+2*16) + 2*16 = 1.71 : 3.29

If u clear up this mess, u r gonna get x = 40. sth sth

 

[ideggkr]

Could someone please solve question number 7 of OCTOBER/NOVEMBER 2005 or click on the link below.

http://www.xtremepapers.me/CIE/Internat ... 5_qp_1.pdf

QUESTION 7

A?

You're right, but how? Could you please explain?

Oh shoot I wrote up everything and i think it's all disappeared.

Anyway, I think enthalpy change of neutralisation depends on how strong an acid/base is.

Strong acid + strong base --> high enthalpy change
and vice versa.

Nitric acid = quite weak acid, ammonia = weak base, KOH = strong base

Hope this helps

 

[kshumaila52]

Could someone please solve question number 7 of OCTOBER/NOVEMBER 2005 or click on the link below.

http://www.xtremepapers.me/CIE/Internat ... 5_qp_1.pdf

QUESTION 7

Ans is A
for P and Q, low heat change means weak acid and base as some energy used for their dissociation, R is strong base (check heat change)

 

[ShootingStar]

Another Question..

 

[Mobeen]

Another Question..

B

 

[kshumaila52]

Another Question..

Ams B