What are collisions and combinationations of gas and matter called

In this chemical reaction, 325 grams of barium (ba) react completely. how many moles of lithium (li) are produced?

Adrop of acetone (nail polish remover) has a mass of 35 mg and a density of 0.788 g/cm3. what is its volume in cubic centimeters?

An object becomes electrically charged when: electrons are created in it electrons from it are destroyed electrons are transferred to it protons from it are destroyed protons are created in it