There are 8 elements that together make up 98.5% of earth crust oxygen 46.6% aluminum 8.1% iron 5.0% calcium 3.6% sodium 2.8% potassium 2.6% magnesium 2.1% and silicon what percentage of earth crust is silicon

Which of these statements is true? a. quarks pair with leptons to form protons and neutrons. b. quarks pair with bosons to form photons. c. quarks pair with photons to form protons and neutrons. d. quarks pair with other quarks to form protons and neutrons. e. quarks pair with electrons to form protons.

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?

How does changing the strength of the fork vibration affect the characteristics of the longitudinal wave? how does changing the frequency of the fork vibration affect the characteristics of the longitudinal wave?