The contents of a rock have a 206Pb to 238U mass ratio of 0.155:1.00. Assuming that the rock did not contain any 206Pb at the time of its formation, determine the age of the rock. Uranium-238 decays to lead-206 with a half-life of 4.5 billion years.

2. you__turn left on a red light if you are in the left-most lane of a one-way street, you're turning into the left-most lane of a one-way street, and no nearby sign prohibits the turn.

Seltzer water is created by placing water under pressure with carbon dioxide gas. which of the following statements best describe seltzer water: a. the solution will be slightly acidic b. the solution will be slightly basic. the solution will be strongly acidic. d. the solution will be strongly basic. e. the solution will be neutral

Which other elements contain the same number of outer electrons as sodium