Laura measures the speed of a ping pong ball when she drops it from different heights using a motion sensor. She notices that the speed of the ping pong ball is roughly the same at the end of its fall for every drop higher than 260 cm. Explain why the final speed of the ball doesn't change after 260 cm.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

the answer is barium and copper bromide

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)