Man has never directly reached the inner layers of the Earth. But what phenomena allow to determine its chemical composition? A)Surface wave propagation.
B)Plate displacement
C)Emanation of lava in volcanoes
D)Changes in the Earth's landscape
E)Waves formed in tidal waves

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions