Diamonds are one of the hardest materials known. Hardness is how resistant a material is to being scratched by another material. If two samples of metal that appear identical
are scratched by a diamond, is that sufficient to determine that they are the same metal?
Why or why not?

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

What shape would a molecule with two bound groups and two lone pairs have?

What rule is used to determine how many covalent bonds an element can form? a. the number of covalent bonds is equal to six c the number of covalent bonds is equal to five minus the group number plus the group number b. the number of covalent bonds is equal to eight d. none of the above minus the group number select the best answer from the choices provided