Amover packs books, cds, and dvds into a moving box. if the box contains 6.5 kg of books, 1.5 kg of cds, and 2.0 kg of dvds, what is the percent by mass of each object in the box?

What does x represent in the formula for the compound xcl4?

What does the cell nucleus do or, how does it function?

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?