Accuracy

Q: The sodium thiosulfate solution was prepared by dissolving 4.5 g of sodium thiosulfate in water and making the solution up to 250 cm^3 in a volumetric flask. The volumetric flask is accurate to 0.3 cm^3 so, to match this accuracy, the mass of the sodium thiosulfate should be accurate to at least

A. 0.5 g
B. 0.05 g
C. 0.005 g
D. 0.0005 g

The answer is C. But why??? I have no clue at all

Please teach me :frown:

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Original post by mystreet091234

Q: The sodium thiosulfate solution was prepared by dissolving 4.5 g of sodium thiosulfate in water and making the solution up to 250 cm^3 in a volumetric flask. The volumetric flask is accurate to 0.3 cm^3 so, to match this accuracy, the mass of the sodium thiosulfate should be accurate to at least

A. 0.5 g
B. 0.05 g
C. 0.005 g
D. 0.0005 g

The answer is C. But why??? I have no clue at all

Please teach me :frown:

(

Calculate the percentage inaccuracy by 100 x 0.3/250

Now take this percentage of the mass needed.