Helplp please 1.The electromagnetic waves described in the reading are different in which two ways:
a. Frequency and amplitude
b. Wavelength and frequency
c. Wavelength and crests
d. Frequency and velocity

i wish i could but this one is weird give me abc and i can solve it.

a is the correct answer

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.