The model of the atom has dramatically changed over many many years.We learned atoms make up different substances and are the smallest particles of matter, which have subatomic particles that are very small portions of matter. At first scientist only thought there were electrons which are negatively charged.
17) 2 - temperature is a measurement
18) 4 - the unit for energy
19) 1 - all others are measurement and stuff
20) 2
21) 4
29) 1 and 3 - energy is being added
It’s a chemical reaction I guess? Or maybe it hits the water and unlike a solid and it being a liquid it goes into the water causing it to spread or something like that.
Count the atoms of each element in the reactants and the products. Use coefficients; place them in front of the compounds as needed.