Suppose that you have a rod that is positively charged, a rod that is negatively charged and a stand that allows rotation. if you are handed a rod of unknown charge-state, could you determine if it has a positive charge, a negative charge or if it is neutral? explain

Yes

Explanation:

The law of electrostatics states that like charges repel, while unlike charges attract. When you place either of the charged rods on the rotating stand, bring the rod of unknown charge-state in its neigbourhood. If there is repulsion, it shows that both rods have same charge, while attraction would show opposite charges. If the rod is neutral, there would be no reaction, since net charge is zero.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.