Earths atmosphere provides needed gases for living things and protect them against radiationfrom the sun. (it doesn't have science but this is a science question.)

Ineed this asap part i: scientific method what is the difference between science and pseudoscience? what is the scientific method?

Asample of hydrated tin (ii) chloride (sncl2) has a mass of 4.90 g. when it is dehydrated, it has a mass of 4.10 g. which is the correct chemical formula for the hydrate? sncl2•2h2o          sncl2•4h2o          sncl2•6h2o

Astring vibrates with a frequency of 10 hz. why can't a person hear the sound waves produced by the vibrating string, no matter how large the amplitude of the waves? out! this is homework and due tomorrow! you so much!