A sample initially contains 150.0 mg of radon-222. After 11.4 days, the sample contains 18.75 mg of radon-222. Calculate the half life of radon-222.

Which of the following statements is false regarding aromaticity? a. the compound must be cyclic b. the compound must be fully conjugated c. the compound must be planar d.the number of electrons in the pi system must satisfy the hückel 4n+2 rule e. the compound must have a neutral charge

Write the symbol for every chemical element that has atomic number greater than 3 and atomic mass less than 12.0 u.

200. ml of 3.00 m nacl solution is diluted to a final volume of 500. ml. what is the molarity of the final solution?