Write the balanced COMPLETE ionic equation for the reaction when Na₂CO₃ and AgNO₃ are mixed in aqueous solution. If no reaction occurs, write only NR.

1) how many electrons are in each energy level of the following elements? a. he b. na c. na d. ne 2) how many valence electrons are percent in the following atoms? a. s b. mg c. be d. cl 3) which of the following elements are stable as atoms? a. he b. o c. cl d. ar if you are able to provide the work as to how you got the answers that would be greatly appreciated. : )

Which of the following is a testable hypothesis? a. if i brush my teeth, i will get fewer cavities than if i don't brush my teeth. b. green toothpaste tastes better than blue toothpaste or red toothpaste. c. smart, careful, healthy people always brush their teeth. d. it's wrong to not brush your teeth before you have an important conversation with someone.

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange