Br2 is miscible or immiscible ? and why ?

Bromine or Br2 is miscible to most nonpolar solvents. And it is also immiscible in polar solvents such as water. It is because there are no lone pairs present in the structure of Bromine making it miscible to most nonpolar solvents.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

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.