How many grams of H2 are needed to react with 2.85 g of N2?

Which is mostly likely why many scientists reject the cold fusion theory

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.

Compare and contrast physical changes with chemical changes.