What is meant by "elastic collisions"?

heat given off by constant collisions,
compression of the gas,
resultant force of all combined collisions, or
collision and rebound without loss of energy

It is important to wear proper protective equipment in lab even when not actively performing experiments because accidents can affect any researcher, even one not working on an experiment. select the best answer from the choices provided

Why are the trends and exceptions to the trends in ionization energy observed?

How many molecules are in 6.0 moles of methane