What kind of chemical do we release when we help others?

Which statement describes both homogeneous mixtures and heterogeneous mixtures?

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!

How many moles are in 123.0 grams of kclo4?