What is Matter?

What are matter waves ?

What are matter waves? Show that de-Broglie wavelength associated with an electron of energy, V-electron volt is approx. 12.27/(sqrtV) Å .

What is the purest form of matter that cannot be separated into different substances by chemical means

What is particular matter? How do particular matters harm human health?

What is the subject-matter of the study of human geography? Explain any three facts.