The symbol ca-40 denotes that

a. a calcium atom contains 40 protons
b. a calcium atom contains 40 electrons
c. a calcium atom contains 40 neutrons
d. a calcium atom has a mass number of 40

This image is an example of a(n) a) atom. b) compound. c) mixture. d) molecule.

How have the greenhouse gasses increased from the year 2000 to 2018

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