For the element Selenium (Se), state: How many principal energy levels (PEL's) it has? How many (PEL's) and which ones are occupied? How many (PEL's) and which ones are full?
How many Sub-Levels it has? How many (sub levels) and which ones are occupied? How many (sub levels) and which ones are full?
How many Orbitals it has? How many (orbitals) and which ones are occupied? How many (orbitals) and which ones are full?

The table lists the lattice energies of some compounds.compoundlattice energy (kj/mol)lif            –1,036licl            –853naf            –923kf            –821nacl            –786which statement about crystal lattice energy is  best  supported by the information in the table? the lattice energy increases as cations get smaller, as shown by lif and kf.the lattice energy increases as the cations get larger, as shown by lif and licl.the lattice energy decreases as cations get smaller, as shown by nacl and naf.the lattice energy decreases as the cations get smaller, as shown by naf and kf.

How many moles of bromine are needed to produce 3.23 moles of potassium bromide

Estimate the molar mass of the gas that effuses at 1.6 times the effusion rate of carbon dioxide.