Why was gold not historically used for tools?

According to the tide table below what time of day will the highest tide occur?

The rules of engagement (roe) working group is often used to (select all that apply.)

In the millikan oil drop experiment they determined that every drop had a charge which was a while number multiple of -1.60x10^-19. if a drop has a total charge of -9.60x10^-19 then how many excess electrons are contained within the drop?