Why did Mendeleev switch the order of some elements in his periodic table

Identify the electromagnets with poles that are reversed from the electromagnet shown above

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?

Movement that is like a t a type of wave that transfers energy where the particles in the medium move in a circle motion while the energy travels left or right. a type of wave that transfers energy where the particles in the medium move perpendicular to the direction in which the energy is traveling. transfers energy from one location to another a type of wave that transfers energy where the particles in the medium move parallel to the direction in which the energy is traveling. movement that is back and forth, like an equal sign = 1. wave 2. parallel movement 3. perpendicular movement 4. transverse wave 5. longitudinal wave 6. surface wave