How can you verify that metals conduct electricity and explain​

delocalised electrons

Explanation:

In a metal there are delocalised(free) electrons which means they carry electrical charge through the metal.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

it's all four options.