Filtering air to remove dust and pollen is it chemical or physical change

Ionic compounds are made of ions, and yet the overall charge of an ionic compound is neutral. why?

How many moles of carbon dioxide will form if 2.5 moles of c3h8 is burned

What method(s) do plants use to obtain nitrogen? select all that apply. absorb it from the atmosphere use bacteria to convert nitrogen to usable form obtain usable nitrogen compounds from the soil absorb nitrogen from water taken in at the roots