PLEASE HELP!! URGENT! AND PLEASE DO EXPLANATION!! The half-life of Lead-214 is 27 minutes. How much of a 169 sample would be left after 81 minutes?

How many atoms are in 1.4 mil of phosphorus trifluoride (pf3)

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

The characteristic of two different types of reactions are shown below. reaction a: electrons are gained by the atoms of an element. reaction b: protons are lost by the atom of and element. which statement is true about the atoms of the elements that participate in the two reactions? a: their identity changes in both reaction a and b. b: their identity changes in reaction a but not b. c: their identity changes in reaction b but not a. d: their identity remains the same.