Help! help! plz 1)What is most important of periodicity lest 4
2)why are energies of
various energy levels in hydrogen atomic are negative?​

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here

Find the mass, in grams, of 5.00*10^23 molecules of f2

An ice cube with a volume of 45.0ml and a density of 0.9000g/cm3 floats in a liquid with a density of 1.36g/ml. what volume of the cube is submerged in the liquid