1- an atom has a mass number of 24 and 13 neutrons. what is the atomic number of this atom?

2-give the nuclear symbol for the isotope of argon for which a=38?
enter the nuclear symbol for the isotope (e. g., 42he).

1.- The mass number of an atom equals the number of neutrons plus the number of protons. Then, for this atom the number of protons equals 24 less 13 = 11. The number of protons is the atomic number, so the answer is that the atomic number is 11.

2.- A = 38, means that the isotope of argon has mass number of 38. Given that the atomic number of argon is 18, this isotope has 18 protons and 38 less 18 = 20 neutrons.Then, the nuclear symbol is Ar precedeed by the numbers 38 (upper left corner) and 18 (lower left corner).

This scenario is called diffusion. particles are moving from regions of high concentration to low concentration.