Which part of the atom is involved in chemical reactions?
a. protons.
b. neutrons.
c. nucleus
d. electrons

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

If a tank filled with water contains a block and the height of the water above point a within the block is 0.8 meter, what is the pressure at point a?

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?