A student has stored 250 mL of helium gas over water on a cool day when the temperature in the room reads 20.5°C. If the barometric pressure in the room is
768 mm Hg, what is the pressure of the helium gas in its container?

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

Which fact represents evidence for the big bang theory?

Give the set of reactants (including an alkyl halide and a nucleophile) that could be used to synthesize the following ether: draw the molecules on the canvas by choosing buttons from the tools (for bonds and charges), atoms, and templates toolbars, including charges where needed. ch3ch2och2ch2chch3 | ch3