Ow many valence electrons do atoms in group 1, group 2, group 15, group 16, group 17 have?

How many grams of n2h4 will be consumed by 23 g of n2o4

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.

What is impossible to do with a hypothesis