what’s the name and formula for potassium (chloride/nitride/sulfide) ? help me please!!! really appreciate it

How do i complete this electrolysis of water lab? i’m at home, so i don’t have the materials, and the lab didn’t properly work and was incomplete at school.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

In 2002, the rare earth elements mine in mountain pass, california was closed because