HELP PLEASE!!Think about the activities you have carried out over the last three days. Describe two activities that involved physical changes and two activities that involved chemical changes. Choose everyday activities. Do not use any activities you did in school as part of a science lab. How do you know which type of change was involved in each case?

Hello,#agreed with joseph002.i got my source also from  source: hope this

For a collision to be successful you need 2 different objects 

I'm pretty sure its c

Van der waals forces are temporary electromagnetic forces established between uncharged atoms. some neutral molecules, when close together, can become temporarily “charged,” as electrons move around the atom. water is a polar molecule, the side of the molecule that the hydrogens bond to being more positive, and the opposite side bound to the lone pairs of electrons being more negative. this means that it participates in dipole-dipole interaction (non-polar exhibits dispersion forces), and it has the capacity for hydrogen bonding.