Which two types of particles exist in equal numbers in an atom? protons and electrons protons and neutrons protons and photons electrons and neutrons

If 10.g of agno3 is available, what volume of 0.25 m agno3 can be prepared

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.

An observation that requires measurement is called quantitative observable or qualitative