Electrons are shared with 2 other atoms with double bonds

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

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.

Use the de broglie's wave equation to find the wavelength of an electron moving at 4.5 × 106 m/s. show your work. note: h= plank's constant (6.62607 x 10-34 j s)