Use the ideal gas law to calculate the pressure in atmospheres of 0.21 mol of helium (He) at 16°C & occupying 2.53 L. You must show all of your work to earn credit. **Don't forget to convert your Celsius temperature to Kelvin**

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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.

Ionic compounds are made of ions, and yet the overall charge of an ionic compound is neutral. why?

Ahydrogen atom has 1 electron. how many bonds can hydrogen form? a) 1 b) 2 c) 3 d) 4 e) 5