Urgent !!!!!!!!!!!!!!!! plzzzzzzzz chem ATP

[Aathi]

oct|nov 2008 P4 Q1 (c) (iv)
AND
Q8 b(ii)

 

[Syed Ali]

Q1,c,vi-- Air : O2
100cm3: 20cm3
x : 30 cm3

x= 3000/20 = 150 cm3


Q8,b,ii-- 1.32 grms of sodium carbonate are dissolved in 250 cm3

Volume : mass dissolved
250 : 1.32
1000: x
x=5.28 grms in 1000 cm3 ( 1 dm3 )

n= mass/Mr

5.28/106 = 0.0498 moles/dm3

Hope that helps!