I need help pt2. I have a major grade due tomorrow and I have 12 questions left and idk how to solve the last 12

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

An ionic compound can conduct electricity when a it is dissolved in water b its crystals are ground into powder c it is in solid form d it is heated to just below its melting point

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.