(PLEASE HELP) Which of the following describes a mixture?

A. Matter that is composed of a single element and has all the same physical properties
B. Matter that is made of molecules of all the same type
C. Two atoms chemically bonded together
D. A substance made of two or more types of atoms that are not chemically bonded

What is a subatomic particle with a negative charge and very little mass?

Aparticle of mass m is placed in a one-dimensional box of length l. the box is so small that the particle’s motion is relativistic, so that e p2/2m is not valid. (a) derive an expression for the energy levels of the particle using the relativistic energy–momentum relation and the quantization of momentum that derives from connement. (b) if the particle is an electron in a box of length l 1.00 1012 m, nd its lowest possible kinetic energy. by what percent is the nonrelativistic formula for the energy in error?

How do you count the total number of atoms present on one side of a chemical equation?