The nerves in her hand are transfering heat into the ice and the ice is transfering cold into her hand until they are the same tempature.
Breathing is the exchange of gases between animals & the environment.
Humans could start using different approaches. For example, fossil fuels are non-renewable resources and this is what most humans use to fuel car engines. However, have you ever heard of battery operated cars? This is a much better alternative to cars that run on gas because, there is not as many toxins that are released into the environment and it will reduce the consumption of fossil fuels that are only so limited. Also, solar panels are way better that running lights on coal, and here is why: Solar energy is a renewable resource and if coal ever runs out, then there will always be another light source. I hope you found this helpful!
O2 is just elemental oxygen. It's a pure substance, but not necessarily because it only contains oxygen atoms, it's because there's only oxygen molecules present.
