Recall the wave equation,

where c is the speed of the wave (m/s), f is the frequency of the wave (Hz) and λ is the wavelength of the wave (m).

so
Ionic bond is a type of bond formed between a non metal and a metal, it involves transfer of electrons that results to formation of ions, normally a cation and an anion. In this case the combinations that will result to ionic bonds include;
NaF, LiCl, NaO2, BeF2, and BeS
An image that appears upside down behind the focal point is an image that is reflected on a concave mirror. Mirrors reflect different kinds of images based on the placement of an object that is reflected towards it. There are two kinds of mirrors, concave and a convex mirrors, the latter makes objects seem smaller and farther than where it is exactly.