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    Can someone help me with these calculations:

    1) The recommended limit for safe exposure to sulfur dioxide in the air is 0.000025%. What is the concentration in parts per million,ppm?
    a)25
    b)0.25
    c)0.025
    d)0.0025

    The answer is B can someone please explain why

    2)Sodium thiosulfate was used to determine the concentration of iodine by titration
    The sodium thiosulfate solution was prepared by dissolving 4.5g of sodium thiosulfate in water and making the solution up to 250cm3 in a volumetric flask. The volumetric flask is accurate to +-0.3cm3 so to match this accuracy the mass of the sodium thiosulfate should be accurate to at least
    a)+-0.5g
    b)+-0.05g
    c)+-0.005g
    d)+-0.0005g

    the answer is C can someone explain why please
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    Sorry you've not had any responses about this. Are you sure you've posted in the right place? Here's a link to our subject forum which should help get you more responses if you post there.
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    (Original post by maths_geek234)
    Can someone help me with these calculations:
    Hi I've moved this to the Chemistry Study Help forum

    Posted from TSR Mobile
 
 
 
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