Please help! its due at the end of class.

Find the mass in grams of 1.37x1020 particles of h3po4

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5

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?