Joan and mike's teacher show them a picture of an atom and ask them to identify it using the periodic table. joan says the atom is carbon, but mike says it is lithium. who is right and why?

Two friends at different locations want to communicate with each other by sending low energy signals. which of the following methods can they use to communicate? a) produce x-rays using colliding electrons and send them to radios, which capture sound b) send messages using infrared radiation, which travel in the form of waves c) send radio waves through intervening media like radio and television d) produce sound waves using microwaves from heated objects

Express the following number in scientific notation. 0.026890 =

Asample of aluminum foil contains 8.60 × 1023 atoms. what is the mass of the foil?