How many atoms are in 4 H2PO4

Harvey kept a balloon with a volume of 348 milliliters at 25.0˚c inside a freezer for a night.  when he took it out, its new volume was 322 milliliters, but its pressure was the same.  if the final temperature of the balloon is the same as the freezer’s, what is the temperature of the freezer? the temperature of the freezer is  kelvins.

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Marcel just purchased 1.69 grams of iron fillings in order to make living putty for his 6 year old niece. how many moles of iron are made in his sample?