How many independent variables can be tested in a standard scientific experiment

Great amounts of electromagnetic energy from our sun and other bodies in space travel through space. which is a logical conclusion about these electromagnetic waves? their energy must be very their frequency must be very low these waves can travel without a medium they only travel through a vacuum of space

Place the elements below in order of decreasing ionization energy. aluminum(al) chlorine(cl) magnesium (mg) sulfur(s)

Two people each hold the end of a rope and create waves by moving their arms up and down. this wave is best classified as a transverse wave because a) both the rope particles and the wave are moving in the same direction. b) the wave is moving up and down as the particles of the rope move horizontally. c) the wave is moving horizontally as the particles of the rope move up and down. eliminate d) the wave is moving in a parallel direction with the motion of the person's arms.