help in chemistry mcq

[RGBM211]

[attachment=0]2011-09-10 21.30.53.jpg[/attachment] May/june 2007 question 2 paper1

 

[destined007]

mole of NxOy= 120/24000 = 5 x 10^-3 mol

mole=mass/Mr
Mr=mass/mole=0.23/5x10^-3
Mr=46

Now put the values of x and y in NxOy and the formula which give Mr as 46 is the answer.
So its B

 

[RGBM211]

dint get it how can you use the volumes to find the mole isn't there like another way where we set up an equation and find x and y directly?

 

[destined007]

there may be other ways but this one is also correct.

24000 cm^3 occupies 1 mole
so 120 cm3 occupies 1/240000 x 120 moles

If some other way also comes into my mind i'll post here.

 

[RGBM211]

thanks

 

[destined007]

Welcome

 

[sadman]

I am sorry I have a question,
Where on earth did the question said which variable in X and which variable is y?
stupid CIE

 

[destined007]

Haha! Actually, it's kinda half printed image. When I opened the actual paper, it's mentined there.