The formula unit for Cr+2 and NO3 -1

B - Cr(NO3)2

Explanation: The +2 on Chromium and the -1 on NO3 indicates the charge. And in order to balance out the charge, you will sometimes need to add more of a substance.

In this case, Cr has a +2 charge and NO3 has a -1 charge. To balance, the total charge needs to equal 0. So, you add another NO3 to make two -1 charges, which will cancel out the +2 charge on Cr.

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.