A teacher has found two wh te powders on a desk in the chemistry laboratory. She wants to test to see if they are pure substances, so she
measures the melting points. Substarce X meits at 1225C and substance Y
meits between 87 and 93°C. Explain which one is the pure substance.

Light waves travel than sound waves.

Elements in group 2 are all called alkaline earth metals. what is most similar about the alkaline earth metals?

I'm learning about the periodic tables and what each subject's configuration is. for example, hydrogen is 1s^1, but i don't understand how you get that. can someone me understand how to figure out how to figure this out? sorry if the question makes no sense, but it would really a lot if you could me understand! you so much if you can!